An abbreviation is a short way of writing a word or a phrase that could a lso be written out in full. So, for example, you might write Dr Kinsey inste ad of Doctor Kinsey. Here Dr is an abbreviation for the word Doctor. Likewise, the phrase for example can sometimes be abbreviated to e.g.

Abbreviations must be clearly distinguished from contractions. The key difference is that an abbreviation does not normally have a distinctive pronunciation of its own. So, for example, the abbreviation Dr is pronounced just like Doctor, the abbreviation oz is pronounced just like ounce(s) and the abbreviation e.g. is pronounced just like for example. (True, there are a few people who actually say "ee-jee" for the last one, but this practice is decidedly unusual.) A contraction, in contrast, does have its own distinctive pronunciation: for example, the contraction can't is pronounced differently from cannot, and the contraction she's is pronounced differently from she is or she has.

Abbreviations are very rarely used in formal writing. Almost the only ones which are frequently used are the abbreviations for certain common titles, when these are used with someone's name: Mr Willis, Dr Livingstone, Mrs Thatcher, Ms Harmon, St Joan. (Note that the two items Mrs and Ms are conventionally treated as abbreviations, even though they can be written in no other way.) When writing about a French or Spanish person, you may use the abbreviations for the French and Spanish equivalents of the English titles: M. Mitterrand, Sr. González. (These are the usual French and Spanish abbreviations for Monsieur and Señor, equivalent to English Mister.) Observe that each of these abbreviations begins with a capital letter.

Other titles are sometimes abbreviated in the same way: Prof. Chomsky, Sgt. Yorke, Mgr. Lindemann. However, it is usually much better to write these titles out in full when you are using them in a sentence: Professor Chomsky, Sergeant Yorke, Monsignor Lindemann. The abbreviated forms are best confined to places like footnotes and captions of pictures.

Note carefully the use of full stops in these abbreviations. British usage favours omitting the full stop in abbreviations which include the first and last letters of a single word, such as Mr, Mrs, Ms, Dr and St; American usage prefers (A) Mr., Mrs., Ms., Dr. and St., with full stops. Most other abbreviated titles, however, require a full stop, as shown above.

A person's initials are a kind of abbreviation, and these are usually followed by full stops: John D. Rockefeller, C. Aubrey Smith, O. J. Simpson. Increasingly, however, there is a tendency to write such initials without full stops: John D Rockefeller, C Aubrey Smith, O J Simpson. And note the rare special case illustrated by Harry S Truman: the S in this name never takes a full stop, because it's not an abbreviation for anything; President Truman's parents actually gave him the middle name S.

Two other common abbreviations are a.m. (`before noon') and p.m. (`after noon'): 10.00 a.m., six p.m. These are always acceptable. Note that these are not capitalized in British usage (though American usage prefers (A) 10.00 am and six pm, with small capitals and no full stops).

Also usual are the abbreviations b.c. and a.d., usually written in small capitals, for marking dates as before or after the birth of Christ:

According to tradition, Rome was founded in 753 b.c.
The emperor Vespasian died in a.d. 79. or
The emperor Vespasian died in 79 a.d.

It is traditional, and recommended, to write a.d. before the date, but nowadays it is often written after.

Non-Christians who do not use the Christian calendar may prefer to use b.c.e. (‘before the common era') and c.e. (‘of the common era') instead. This is always acceptable:

According to tradition, Rome was founded in 753 b.c.e.
The emperor Vespasian died in 79 c.e.

All four of these abbreviations are commonly written in small capitals, and you should follow this practice if you can; if you can't produce small capitals, use full-sized capitals instead. All four of them are also now very frequently written without full stops: 753 bc, ad 79, 753 bce, 79 ce. This reflects the increasing tendency to omit the full stops in abbreviations, and I myself prefer to write 753 bc, and so on.

Note also that, when an abbreviation comes at the end of a sentence, only one full stop is written. You should never write two full stops in a row.

Many large and well-known organizations and companies have very long names which are commonly abbreviated to a set of initials written in capital letters, usually with no full stops. Here are a few familiar examples:

British Broadcasting Corporation
Imperial Chemical Industries
Federal Bureau of Investigation
Royal Society for the Prevention of Cruelty to Animals
North Atlantic Treaty Organization
Massachusetts Institute of Technology
Trades Union Congress

These and some others are so famous that you can safely use the abbreviated forms without explanation. But don't overdo it — not every reader will recognize IRO as the International Refugee Organization, or IOOF as the Independent Order of Odd Fellows (an American social and charitable organization). And, if you're writing for a non-British readership, you'd better not use the abbreviated forms of specifically British institutions, such as the TUC, without explaining them. If you are in doubt, explain the abbreviation the first time you use it. (Note that a few of these were formerly written with full stops, such as R.S.P.C.A., but this tiresome and unnecessary practice is now obsolete.)

A few other abbreviations are so well known that you can use them safely in your writing. Every reader will understand what you mean by GCSE examinations (GCSE = General Certificate of Secondary Education), or by DDT (dichlorodiphenyltrichloroethane), or by IQ (intelligence quotient), or by FM radio (FM = frequency modulation). Indeed, in some of these cases, the abbreviated form of the name is far more familiar than the full name.

Otherwise, however, you should try to avoid the use of abbreviations in your formal writing. The frequent use of unnecessary abbreviations will make your text irritating and hard to read. So, you should write four ounces (not 4 oz.), 80 miles per hour (not 80 mph), the Church of England (not the C of E), the seventeenth century (not C17 or the 17th cent.) and the second volume (not the 2nd vol.) It is far more important to make your writing easy to read than to save a few seconds in writing it.

There is one exception to this policy. In scientific writing, the names of units are always abbreviated and always written without full stops or a plural s. If you are doing scientific writing, then, you should conform by writing 5 kg (not 5 kilogrammes, and certainly not *5 kg. or *5 kgs.), 800 Hz (not 800 Hertz) and 17.3 cm3 (not 17.3 cubic centimetres).

There are a number of Latin abbreviations which are sometimes used in English texts. Here are the commonest ones with their English equivalents:

e.g. for example
cf. compare
i.e. in other words
v. consult
viz. namely
etc. and so forth
sc. which means
et al. and other people
ca. approximately

The rule about using these Latin abbreviations is very simple: don't use them. Their use is only appropriate in special circumstances in which brevity is at a premium, such as in footnotes. It is very poor style to spatter your page with these things, and it could be disastrous to use them without being quite sure what they mean. If you do use one, make sure you punctuate it correctly. Here is an example. The recommended form is this:

Several British universities were founded in the Victorian era; for example, the University of Manchester was established in 1851.

The following version is not wrong, but it is poor style:

Several British universities were founded in the Victorian era; e.g., the University of Manchester was established in 1851.

But this next version is disastrously wrong, because the punctuation has been omitted:

*Several British universities were founded in the Victorian era e.g. the University of Manchester was established in 1851.

Using a Latin abbreviation does not relieve you of the obligation of punctuating your sentence. Again, if you avoid Latin abbreviations, you won't get into this sort of trouble.

The abbreviation ca. `approximately' is properly used only in citing a date which is not known exactly, and then usually only if the date is given in parentheses:

The famous Basque cemetery of Argiñeta in Elorrio (ca. ad 883) shows tombs with sun-discs but no crosses.
Roger Bacon (ca. 1214–1294) was known as "the Admirable Doctor".

Here the use of ca. shows that the date of the cemetery and the date of Bacon's birth are not known exactly. If neither birth date nor death date is known for sure, then each is preceded by ca.

Outside of parentheses, you should usually avoid the use of ca. and prefer an English word like about or approximately:

The city of Bilbao was founded in about 1210.

Do not write " ca. 1210".

The abbreviation etc. calls for special comment. It should never be used in careful writing: it is vague and sloppy and, when applied to people, rather offensive. Do not write something like this:

*Central Africa was explored by Livingstone, Stanley, Brazza, etc. Instead, rewrite the sentence in a more explicit way:
Central Africa was explored by Livingstone, Stanley and Brazza, among others. or
Central Africa was explored by several Europeans, including Livingstone, Stanley and Brazza.

If you do find yourself using etc., for heaven's sake spell it and punctuate it correctly. This is an abbreviation for the Latin phrase et cetera `and other things', and it is pronounced ET SETRA, and not *EK SETRA. Do not write ghastly things like *ect. or *e.t.c. Such monstrosities make your writing look hopelessly illiterate. Again, if you avoid Latin abbreviations, you won't fall into such traps.

Finally, there are two further (and highly objectionable) Latin abbreviations ibid. and op. cit.

Observe that it is usual to write Latin abbreviations in italics, but this is not strictly essential, and many people don't bother.

There has recently been a fashion in some circles for writing Latin abbreviations without full stops, and you may come across things like ie and eg in your reading. I consider this a ghastly practice, and I urge you strongly not to imitate it. (Note, however, that et al. has only one full stop, since et `and' is a complete word in Latin.)

One final point: very many people who should know better use the Latin abbreviation cf., which properly means `compare', merely to refer to published work. It is now very common to see something like this:

*The Australian language Dyirbal has a remarkable gender system; cf. Dixon (1972).

This is quite wrong, since the writer is not inviting the reader to compare Dixon's work with anything, but only to consult that work for more information. Hence the correct form is this:

The Australian language Dyirbal has a remarkable gender system; see Dixon (1972).

This widespread blunder is a signal reminder of the danger of using Latin abbreviations when you don't know what they mean. Far too many writers fall into this trap, and write i.e. when they mean e.g., or something equally awful. If you must use a Latin abbreviation, make sure you're using the right one. In most circumstances, though, you are best advised to avoid these abbreviations: almost every one of them has a simple English equivalent which should usually be preferred.

Summary of abbreviations:

  • Do not use an abbreviation that can easily be avoided.
  • In an abbreviation, use full stops and capital letters in the conventional way.
  • Do not forget to punctuate the rest of the sentence normally.

Copyright © Larry Trask, 1997

Maintained by the Department of Informatics, University of Sussex