Initialisms, Acronyms, and Contractions

Basics | Details | Glossary | References | Images
Before reading the rest of this section, ask yourself: “Do I want to abbreviate or shorten a word or phrase to save keystrokes or to aid the reader?” If your answer is “the reader,” you’re on the right track. Do not use an abbreviation or acronym that your readers would not recognize quickly. When in doubt, spell it out.


An abbreviation is a shortened form of a word or phrase. The Chicago Manual of Style distinguishes between acronyms, initialisms, and contractions, all under the umbrella of abbreviation. They are defined as follows:

  • acronym refers only to terms based on the initial letters of their various elements and readable as single words (NATO, AIDS),
  • initialism to terms read as a series of letters (BBC, ATM), and
  • contraction to abbreviations that include the first and last letters of the full word (Mr. for mister or master).

Acronyms, Initialisms & Abbreviations Dictionary (4 vol. set)Humans seem to have an almost endless interest in shortening things. An excellent reference work is Acronyms, Initialisms, and Abbreviations Dictionary, edited by Mary Rose Bonk and published in its twenty-seventh edition in 2000 by Gale Research Incorporated. It is a four volume set.

The Basics

1. When in doubt spell it out—at least the first time.

The purpose of writing is communication, and anything that may cause confusion should be avoided. The first time you use an abbreviation, initialism, or acronym, spell it out and present the short version in parenthesis: The Greater Reno Water Authority (GRWA) calls for the use of native desert plants in all yards and gardens.

2. Use abbreviations and acronyms if you are certain your reader understands them.

In general, use abbreviations only in charts, tables, graphs, footnotes, bibliographies, and other places where space is at a premium.

Reference the full name first in the body of the text with the abbreviation in parenthesis. For example, NASA may mean the National Aeronautics and Space Administration, National Auto Sport Association, National Assistance Services Australia, etc.

    • In the text: The National Aeronautics and Space Administration (NASA) has improved its troubleshooting protocols significantly in the last five years (see illustration 2).
    •  Within the illustration: Illustration 2. NASA’s ten year troubleshooting record.

3. Introductions are important.

The first time you use an abbreviation or acronym that might be misunderstood by any part of your potential five year audience*, spell it out and then put the abbreviation in parenthesis. The average reader tends to know only the most popular acronyms. Here are some helps:

The CIA World Factbook Appendix A: Abbreviations lists international abbreviations and Appendix B: International Organizations and Groups contains information about missions and memberships of international organizations.

Abbreviations and Acronyms of the U.S. Government includes links to Internet servers when available.

Acronym Finder covers common acronyms, computers, technology, and telecommunications, with an emphasis on Department of Defense (DoD), Air Force, Army, and Navy acronyms.

When readers may know the full name best or are unlikely to be familiar with either, spell it out first. Examples:

  • The Congressional Budget Office (CBO) figured the annual cost of that bill to be 17 billion dollars greater if McDuffy’s amendment were added.
  • The Nuclear Energy Agency (NEA) showed safety-related issues at Three Mile Island (TMI) that were similar to those found at the Fukushima Nuclear Power Plant.

When it’s the acronym that we know or the entity goes by:

  • The official name of the company is TSYS, which stands for Total Systems Services, Inc. Because TSYS is the name they go by, the whole name is what goes in parenthesis: TSYS (Total Systems Services, Inc.).
  • The space agency is best known to most of us by its acronym, so it makes sense to use that first: The NASA (National Aeronautics and Space Administration) budget was slashed by 16% this year.

4. Abbreviations in business and agency names, countries, and states begin with a capital letter and end with a period except for the ampersand (&).

When using the traditional form of abbreviation, use commas to offset them: Washington, DC, was built on what was essentially swampland. Note that the term is District of Columbia, but the abbreviation is not D of C. Generally, we leave the little words like determiners and prepositions out. However, earlier we saw that the Department of Defense calls itself the DOD…among other things. (There are actually seven ways to abbreviate those three little words.) That’s fine. I’m not about to argue about abbreviations and acronyms with anybody who’s that much more powerful and better armed than I am, and the military glories in its abbreviations. Would you believe that there’s a DODISS: Department of Defense Index of Specifications and Standards.

Increasingly, in the interest of speed and space, abbreviations are omitting periods. Acronyms and initialisms always leave them out (CIA, not C.I.A.).

Green check mark Countries, States, and ZIP codes: The state of Pennsylvania is in the United States. North America is a continent which includes Canada. The Americas include North America, South America, and Central America. Is United States abbreviated U.S. or US? It depends. Major newspaper style guides (Associated Press Stylebook and The New York Times Manual of Style and Usage) recommend U.S. (periods, no space). Major scientific style guides and The Chicago Manual of Style currently omit periods in capitalized abbreviations: US. (Never write it U S.) The domain root, by the way, is .us on the web.

a. ZIP vs. state abbreviation. Is it correct to use the ZIP code in the body of a text as the state’s abbreviation? The experts differ on that one.

  • Perspective 1: Richard Norquist says yes: “The two-letter, no-period state abbreviations recommended by the U.S. Postal Service (see Postal Abbreviations in the chart below) should always be used where a ZIP code follows. These postal (or ZIP code) abbreviations may also be used in any context where abbreviations are appropriate.”
  • Perspective 2: Many editors, however, will tell you that it’s wrong to conflate the ZIPs and state abbreviations. Their advice: Do not confuse the mailing (ZIP) code with the state or province abbreviation. Use the former on envelopes and inside addresses, the latter everywhere else. Examples:
    • On the envelope and inside address, my ZIP is PA 17601.
    • When the state of Pennsylvania is abbreviated in the body of the text, it’s Pa.

b. Do not use commas with ZIP codes (Lancaster, PA 17601 and not Lancaster, PA, 17601). In general prose, do not substitute the ZIP for the abbreviation. In the body of the letter: Lancaster, Pa. In the inside address and on the envelop: Lancaster, PA 17601.

Green check mark Organizations:

  • In formal writing, write out the full name of the organization.
    The legal abbreviations Inc. and Ltd. may be abbreviated.
  • When in doubt, check the company’s website to see how it refers to itself (or they refer to themselves–corporations and partnerships may choose to refer to themselves singly or in the plural). A corporation is a single entity, however, even when it has wildly disparate divisions, as is the case with General Electric.

5. In formal writing, avoid informal emoticons and abbreviations often found in personal email, Twitter, etc.


  • E-mail should not contain abbreviations beyond “FYI” because most are new slang not familiar to everyone. Remember as well that in a very real sense, it is not you who are writing, it is your firm, agency, school district, etc. In general, you should not need to explain that IBM or Aunty Ann’s is lol.
  • Emoticons are cute in personal writing, but may seem to some readers to be immature for university or professional writing.  In general, avoid such things as 😉 or 🙁 .Why? You’re a big kid now! Irony does not always work well cross-culturally in academic or professional writing. Note: Some writing coaches encourage the use of emoticons as a way of maintaining reader interest. As with all rules, stick with your style-sheet.

6. When to use i.e. and e.g. They are abbreviations for Latin phrases: id est (“that
is”, “in other words”) and exempli gratia (“for the sake of example”).

  • Use “i.e.” when you want to rephrase something you’ve already said, and use “e.g.” when you want to offer an example.
  • Put a comma before and after if you do not use parenthesis; avoid using both i.e. and e.g. in the same sentence; and try not to use either in formal prose. Remember: If you put the material in parenthesis, do not use a comma before.
  • If you start a list with “e.g.,” there’s no need to put “etc.” at the end.

If the applicant is currently one of our tuition-paying clients, i.e., a student, the fee may be waived.

Use plastic wrap when refrigerating items with a strong odor (e.g., fish or onions).

The best ingredients for pizza are green, e.g., spinach, artichokes, and green peppers. The best ingredients for pizza are green: spinach, olives, etc.

7. Capitalize abbreviations if the words they stand for would be capitalized, otherwise stick with lower case.


  • UCLA (University of California at Los Angeles)
  • p. 46 (page 46) Note: some style books omit the period after the ‘page’ abbreviation or omit the ‘p’ entirely (e.g., CMS 2003, 271). Check the appropriate style book for your discipline.

8. Use a period? As usual, there are people who prefer to add periods (Ph.D.) as well as those who insist they should be omitted, and both sides are passionate about it.

The Chicago Manual of Style suggests this general rule: “Use periods with abbreviations that end in a lowercase letter: p. (page), vol., e.g., i.e., etc., a.k.a., a.m., p.m., Ms., Dr., Ph.D., etc. (CMS 10.4 p. 498). The MLA Style Manual, on the other hand, leaves out the periods (269 ff). Here, check both your style sheet of choice and your institution. Both are highly opinionated on this subject…and equally adamant in their certitude.

  • Ms. even though it’s not technically an abbreviation, following Webster’s 11th Collegiate, which suggests that Ms. is a shortened form combining ‘Miss’ and ‘Mrs.’ Also, it’s Ph.D. and Ed.D., but M.S. or M.A.
  • You may wish to use BCE (Before the Common Era) and CE (Common Era) instead of BC and AD. As you can see, none require periods according to the Chicago Manual of Style, though some style manuals retain them. BC, CE, BCE, and AD are always capitalized. A curiosity: At least this week, each letter in all abbreviations is followed by a period in the New York Times style sheet, though the Chicago Manual of Style currently omits them. Whichever you choose, be consistent.

    What is being abbreviated?

    • B.C.E. and C.E. [before the Common Era, Common Era]are more commonly being used in a world dating system, as they are religion neutral. Because various religions use different dating systems, this avoids confusion. Some examples: In the Islamic system, it is currently 1435 Hajri, while according to the Jewish calendar today is 23rd of Tamuz, 5774. According to the Buddhist system, it’s 2557. There are even more possibilities, and that is precisely the point. World communications and commerce require a common date system.
    • B.C. [before Christ] and A.D. [anno domini, in the year of our Lord]. Archaic usages except in specifically Christian materials. Note: some Christians when spelling out the Latin, capitalize Domini as a reference to God (as opposed to god or gods).

    Increasingly, firms are leaving the periods out of these. Always differ to your discipline’s or firm’s style sheet in this.

    If you wish to use C.E., B.C., B.C.E., or A.D. in a sentence referring to a century, the abbreviation follows the century (15th century C.E.). In general, c. 1500 means in about 1500. Curiously enough, while C.E., B.C. And B.C.E. always follows the date; A.D. may either precede or follow a numerical date, depending upon the style sheet. William Safire very firmly notes that, “Correct dating usage is to put B.C., ”before Christ,” after the year and A.D., ”in the year of our Lord,” before the year [my emphasis].” The A.P. Stylebook and the N.Y.T. Manual of Style agree on this one. According to that system, it is currently A.D. 2014, while Babylon fell in 539 B.C. Writing for secular, international consumption, it makes sense to utilize CE and BCE with or without periods depending upon your discipline’s style sheet.

    Green check mark Correct: Alexander ruled in the fourth century BCE.
    (Abbreviation always follows century reference.)

    Green check mark Correct: Charlemagne was crowned
    in CE 800.

    Green check mark Correct: Charlemagne was crowned
    in 800 CE. (Either way is OK for CE. and a number.)

9. Writing a press release or other document for the general public. Here are some tips for writing your headlines from

  • Do not include the terms “Company”, “Incorporated” or “Limited” or their abbreviations unlessthey are necessary to clearly identifythe organization, i.e. Tandy Corporation vs. Tandy Brands.
  • In newspapers, corporate newsletters, and advertising:
    • Do not use first names or middle initials unless it is necessary to clearly identify the individual or to make the headline read correctly. For example: “King of Los Angeles Awarded Congressional Medal of Honor” should be changed to read “John King of Los Angeles Awarded Congressional Medal of Honor.”
    • Do not use headers that look like spam. Anything with repeated exclamation points, dollar signs or all caps will essentially guarantee that the editor will hit the delete key without reading your release.
    • Use words like claim or alleged rather than controversial, potentially libelous, critical or judgmental statements. For example, for the headline “Municipal Hospital Workers Locked Out,” change the headline to “Local 1040 Claims Municipal Hospital Workers Locked Out.”

10. Information unknown: n.p., s.l., or s.n.?

Green check markThe abbreviations “s.l.” and “s.n.” stand for the Latin terms sine loco (without place [of publication]) and sine nomine (without name [of publisher]). They also happen to coincide with French bibliographic apparatus, standing for, respectively, sans lieu (de publication) and sans nom (de maison d’édition). They might also stand for Spanish sin lugar (without) and sin nombre (nameless).

Green check mark These are perhaps superior to the English “n.p.,” which must stand equally for “no place,” “no publisher,” or “no page,” but in English publications “n.p.,” used correctly, is more likely to be understood; The Chicago Manual of Style recommends “n.p.” Note that “n.p.” can stand in for both publisher and place, if neither is known.

11. A.M. and P.M. may either be written in all capital letters or all lower case, but choose one style and stick with it. These abbreviations may be used in all types of writing but only with numbers or a numerical reference. The Brits leave out the periods (e.g., 8 am), but here in the U.S. you shouldn’t. People in the U.S. are likely to think you mean the word ‘am’ and misread, or at least have to pause to see what it is you really mean.

Green check mark None of these abbreviations are separated by commas.

Incorrect: We will meet in the p.m. (OK informally; not standard use, no number.)
Correct: We will meet at 1:15 p.m.

Green check mark Since a.m. means “before noon” and p.m. means “after noon,” use no other expression of time of day with them.

Incorrect: He arrived at 10 p.m. in the evening. (In the evening is redundant)
Correct: He arrived at 10 p.m.
Correct: He arrived at 10 in the evening.

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The Details

A or an with an acronym or abbreviation? Pronunciation rules here. The question arises: When should I use the determiners a, an, or the with acronyms, initialisms, and abbreviations in a sentence? For a vs. an, focus on the sound (your own phonetic pronunciation) rather than the letter. Using the abbreviations in the entry above, that would be (with my pronunciation) an RLO and an Archive Librarian, but a SIRMO. And a partridge in a pear tree.

Apostrophe + -s in plurals of abbreviations? Some style sheets suggest that an apostrophe be added to plural abbreviations like M.D.’s and M.R.I.’s. Others are adamant in insisting that the apostrophe is wrong — that it indicates a possessive and should not be used in a plural like this. Here is a place where it’s useful to have a copy of your discipline’s style book. I tend to say M.D.s and M.R.I.s (this week), but that’s just me saving a keystroke, probably. In practice, I tend to stay out of the way when the big kids fight about things that I’m not terribly invested in. If I pick a style-sheet and stick with it, at least my choice is defensible should anybody take issue with it. Corbett notes that,

“Style rules at The Times (and some other publications, including the Chicago Manual of Style) do call for using an apostrophe in the plural of abbreviations that include periods. The idea is that a combination of uppercase letters, periods and a lowercase ‘s’ is confusing at first glance, and that the apostrophe helps a reader see that the ‘s’ has been added to make a plural.”

Well, OK, then. That suggests that the jury’s still out on that one, but some pretty big guns back the apostrophe (M.D.’s). Still, authorities fight fiercely about these things, so it’s wise to look it up and go with the style sheet your professor, textbook, company, or government agency uses or recommends. Just don’t be surprised when that varies from one venue to another. (Back)

Record management and managers: The length of time material is archived varies widely. The officers who function as librarians and record keepers are sometimes abbreviated, and you should recognize these. Many firms have a Records Liaison Officer (RLO) or Senior Information Resources Management Officer (SIRMO). Others have Archive Librarians, but that term is rarely abbreviated. This is both a legal and a resource issue, and many firms have a Records Help Desk and/or a Records Management Manual. (Back)

Glossaries and live links: In long documents, even when you define an acronym or abbreviation at first use, it can be difficult to find the sentence in
which the term was spelled out, and readers are likely to become frustrated trying to go back and find the identifying sentence several pages (or chapters) later. In addition, many specialized terms are not familiar to the general reader (that would be anybody outside your own field). So, be kind. When writing a book or long report, create a glossary to help the reader keep track of specialized acronyms, terms and abbreviations in longer documents. These days, you can usually get your editor or editorial assistant to live link the glossary entries to the actual usage of such terms in text. Even with the existence of such links, however, it is helpful to define at first use. Some general rules:

  • If an abbreviation or acronym of the term or name would not be clear on second reference, avoid using it. Instead, use a shortened version of the name or a generic word, such as the agency, the committee, the department or the company. Then, not that use (e.g., NABA henceforth, the agency).
  • When possible, avoid following the name of an organization, project or program with an abbreviation or acronym in parentheses or set off by dashes: Endangered Species Act (ESA).
  • Do not provide an abbreviation or acronym after spelling out a term if the shortened version isn’t used elsewhere in the document.
  • Sometimes, when an abbreviation is likely to be more familiar than the spelled-out term, try putting the longer version in parenthesesafter the abbreviation. Or introduce the longer term once soon after using the abbreviation.
  • When the word ‘the’ is part of the company name, it is usually omitted from the acronym.
  • Spell out (don’t abbreviate) all words and phrases in direct quotations if that’s they way they were expressed by a speaker or writer: “We were in Santa Fe, New Mexico, on October 6th.”

There are official sites for abbreviations and acronyms. One that is used worldwide is the CIA World Factbook Appendix on Abbreviations. In fact, it is a very useful tool to know exists for many purposes. Because it is a government agency, CIA Word Factbook data is ‘free use,’ meaning that anyone can use the material without payment or breaking copyright law, though of course you always cite it as your source.

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Glossary: Standard Abbreviations
(A short list of those in most common usage)

See the full list used by the Oxford English Dictionary.

Common Abbreviations

abr., [abridged]

b. [born, brother]

B.C.E. [before the Common Era] or BCE. Sometimes referenced as ‘before the Christian era’.

B.C. [before Christ] or BC

C [Celsius, centigrade, consonant, cytosine]

c. [capacity, century, chapter, copy, copyright]; use c or ca before the number as the abbreviation for circa ‘about’ (as c 1700) but c. after the number for century (as 19th c.).

C.E. [Common Era.] or CE (BCE for Before the Common Era). Note: some people have come believe that the C. stands for Christian, but that would keep it from being commonly used as a more universally applicable alternative to B.C and A.D.

comp. [compiler, compiled by]

ed. [editor, edited by]

n.d. [no date (of publication)]

n.p. [No place (of publication)]

Ph.D. – Doctor of Philosophy (most universities) Rare: DPhil – Doctor of Philosophy (Oxford University and a few others)

pseud. [pseudonym of]

trans. [translated, translated by; translator]

Latin Abbreviations

A.D. [anno Domini, in the year of our Lord] or AD (slowly being superseded by CE (common era).

a.m. [ante meridiem, before noon; anno mundi, in the year of the world] The latter is fairly rare these days. In the 21st century, who dates anything from the date the planet cohered from space dust?

A.M. [artium magister, Master of Arts]

c or ca. vs c. [the first pair abbreviate circa, meaning about,
approximately; the second, with the period, means century]

  • Use c (as c 1700) circa before the date when you mean about or approximately.
  • Use c. (as 19th c.) after the date when you mean century.

cf. [confer, compare]

e.g. [exempli gratia; for the sake of example].

  • When you mean for example, use e.g. John is fascinated by what he calls ‘bugs’ (e.g., spiders and mice).
  • When you mean that is,use i.e.Example: I am told that the best way to catch a unicorn is with a virgin (i.e., a—usually—young person with no sexual experience) or if that fails, with peanut butter and jelly sandwiches.

et al. [et alii, and others]; notice that there is a period only after al., because et is the full Latin word, and not an abbreviation.

ibid. [ibidem, in the same place]

id. [idem, the same]

i.e. [ id est, that is]

inf. [infra, below]

MS (pl. MSS) [manuscriptum, -a, manuscript, manuscripts]

MS [magister scientiae, Master of Science]

pass. [passim, throughout]

PhD [Latin philosophiae doctor or doctor philosophiae] Use with a comma. Goes after the name when Dr. is not in the front of the name. Bonnie Duncan, PhD or Dr. Bonnie Duncan. Never both. Old fashioned way was Ph.D., which may still be used if the publication is more formal/conservative.

p.m. [post meridium, after noon] By definition, 12 a.m. denotes midnight, and
12 p.m. denotes noon, but there is sufficient confusion over these uses to make
it advisable to use 12 noon and 12 midnight where clarity is required.

q.v. [quod vide, which see]

s.l., s.n. [sine loco without place (of publication); sine nomine without name (of publisher)

sup. [supra, above]

s.v. [sub verbo, sub voce, under the word]

ut sup. [ut supra, as above]

vs. or v. [versus, against]

viz. [videlicet, namely]

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References STANDS4 Network. 2004. Web. Found 3 August, 2014.

Acronym Finder. 1988-2014. Web. Found 3 August 2014.

Bonk, Mary Rose. Acronyms, Initialisms, and Abbreviations Dictionary, edited by Mary Rose Bonk (27th ed.) Gale Research, 2000.

CIA. CIA Word Factbook. “CIA World Factbook Appendix on Abbreviations.” 2005. Found 15 December 2005.

Corbett, Phillip. “After Deadline: Newsroom Notes on Usage and Style.The New York Times. 13. April 2010. Found 30 May 2014.

Garbl’s Writing Center. “Style Manual.” Web site manager: Gary B. Larson, Seattle, Washington. Updated 21 November 2005. Found 23 December 2005.

Indiana University. “The Oxford English Dictionary List of Abbreviations.” (n.d.) Found 21 December 2005.

Online Abbreviation Dictionary. 2014. Web. Found 3 August 2014.

Purdue University. Journal Abbreviation Resources. 16 August 2004. Found 21 December 2005.

Purdue University. “The Owl at Purdue.” 2005. Found December 4, 2005.

“Q&A.” The Chicago Manual of Style Online. The Chicago Manual of Style. 2010. Found 30 May 2014.

Safire, William. “B.C./A.D. or B.C.E./C.E.?” New York Times. 17 August 1997.


Dorky Smiley. (n.d.) Web. 29 June 2014.

La dame à la licorn (Tapestry) One of a set of six tapestries, this one denoting ‘sight’. Jean-Baptiste Vermay. ” Musee de Cluny.

Little Girls Fighting. Host website unknown. It’s linked at Web. 29 June 2014.

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