Abbreviations in Writing

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An abbreviation is a shortened version of a written word or phrase used to replace the original. Here are some examples of abbreviations:
  • RAF is short for Royal Air Force.
  • Prof. is short for Professor.
  • CNN is short for Cable News Network.
  • M.O.T. is short for Ministry of Transport.
  • Mr. or Mr is short for Mister.
  • ("Mr." (with a period) is expected in the US. Outside the US, "Mr" is acceptable. There is more on this to come...)
As these examples prove, abbreviations come in different forms. Here is an infographic showing the different types of abbreviations.

types of abbreviation

The Different Types of Abbreviation

Abbreviations usually fall into one of four categories:

(1) Acronyms

An acronym is an abbreviation spoken like a word. For example:
  • DOS
  • (Disk Operating System)
  • (Navy, Army, and Air Force Institutes)
  • (Buy One Get One Free)
Through common usage, a few acronyms have become words in their own rights. Examples include "sonar," "radar," "laser," and "scuba." Nowadays, these are rarely capitalized.

Some acronyms have not yet made a full transition to "recognized word" and can be written with all capital letters or just an initial capital letter (e.g., NATO or Nato).

Read more about acronyms.

(2) Contractions

A contraction is a contracted version of a word. (A contraction often includes an apostrophe to replace any missing letters.) For example:
  • You're
  • (In full: You are)
  • Can't
  • (In full: Cannot)
  • Mr.
  • (In full: Mister)
There are two kinds of contraction:
  • A Contraction with an Apostrophe. This type shortens a word or merges two words into one by replacing the missing letter(s) with an apostrophe. For example:
    • don't
    • can't
    • shouldn't
  • A Contraction without an Apostrophe. This type compresses a word. For example:
    • Mr.
    • Revd.
    • Prof.
Read more about contractions.
Read more about using apostrophes to replace missing letters.
Read more about using periods (full stops) in contractions.

(3) Initial Abbreviations (or Initialisms)

An initialism is an abbreviation whose letters each represent a word. For example:
  • AQI
  • (Air Quality Index)
  • MLRS
  • (Multiple Launch Rocket System)
  • ITV
  • (Independent Television)
Initialisms can be written with or without periods (full stops). The most common practice is to avoid periods. However, when using company names, copy the company's version.

Read more about periods (full stops) in abbreviations.

(4) Syllabic Abbreviations

A syllabic abbreviation is an abbreviation formed from the initial syllables of multiple words. For example:
  • Interpol (International Police)
  • INMARSAT (International Maritime Satellite)
  • Gestapo (Geheime Staats Polizei)
  • Comintern (Communist International)

Why Should I Care about Abbreviations?

Here are five good reasons to think a little more carefully about abbreviations.

(Reason 1) Don't use the word "acronym" for an initialism.

The words "acronym" and "abbreviation" are not synonyms (i.e., they do not mean the same thing). Remember that abbreviations like BBC and CNN are not acronyms but initialisms. Acronyms are spoken like words.
  • There is a list of acronyms at the back of the document.
  • (This is a common statement made at the start of formal documents. The list at the back is always a list of abbreviations, some of which are acronyms.)
Read more about acronyms.

(Reason 2) Be consistent with periods (full stops).

Initialisms can be written with or without periods. Not using periods is far more common than using them. For example:
  • BBC
  • (This is the most common convention.)
  • B.B.C.
  • (This is an acceptable convention. If you adopt it, remain consistent throughout your document.)
Whatever convention you use, be consistent. There is only one ruling that will trump your striving for consistency: If you're writing the name of a company, adopt whatever convention the company uses for itself.

Read more about periods in abbreviations.

(Reason 3) Know when to use periods (full stops) with contractions.

Contractions that do not use apostrophes (e.g., "Dr." and "Prof.") are followed by periods in America. Outside America, the guideline is to use a period only if the last letter of the contraction is different from the last letter of the whole word. For example:
  • Dr. ()
  • (This version is expected in America. It is also accepted outside America.)
  • Dr ()
  • (This version is widely used outside America. No period is required because the last letter of "Dr" and "Doctor" are the same.)
  • Dr ()
  • Prof. () ()
  • (This version is expected in America. It is also expected outside America because the last letters of "Prof" and "Professor" are different.)
  • Prof ()
  • (This version is accepted outside America.)
Read more about periods with contractions.

(Reason 4) Form the plurals of abbreviation correctly.

The plural of an abbreviation is formed by adding "s." Do not use an apostrophe. For example:
  • RTA > RTAs
  • (RTA = Road Traffic Accident)
  • SME > SME's
  • (SME = Small to Medium Enterprise)
Be aware, however, that the plural of an awkward abbreviation can be formed by adding 's. Generally, this is something to be avoided, but, if the author believes the apostrophe helps readers, it can be added. For example:
  • COS > COS's
  • (COS = Chief of Staff)
  • COS > COS'S
  • (An apostrophe is useful when only capital letters can be used, e.g., in titles.)
Read more forming the plurals of abbreviations.

(Reason 5) Be consistent with writing units of measurement.

When using units such as "mph" or "cm," you can either use a space after the number or not. The choice is yours. However, be consistent throughout your document.
  • 700mph, 99m, 10cm, -4°C
  • 700 mph, 99 m, 10 cm, -4 °C
Interactive Exercise
Here are three randomly selected questions from a larger exercise, which can be edited, printed to create an exercise worksheet, or sent via email to friends or students.

See Also

i.e. or e.g.? Using AD, BC, BCE and CE Full stops (periods) in contractions Forming the plurals of abbreviations Using full stops (periods) in abbreviations Take a test on abbreviations What are acronyms? What are contractions?