Which is better usage: USA or U.S.A.?

The punctuation of abbreviations is an area that is subject to considerable differences of opinion. For example, as demonstrated by the question above, not everyone agrees on when (or if) to use full stops.

It’s an indication of just how confused this area is that even the basic terminology isn’t agreed upon. You’d think that a simple term like abbreviation was easy to define, wouldn’t you?

Sure you would, yet some camps distinguish between abbreviations and contractions (giving each different punctuation rules), while others lump everything in together as abbreviations.

A common definition of “abbreviation” goes something like this:

An abbreviation is a shortened version of a word or phrase

and is often followed by a period. For example, c.o.d., ft-

lb, St. or publ.

Unfortunately, there is rarely an explanation of what is meant by “often followed by a period”. So we’re left to wonder *when* does an abbreviation take a full stop, and when doesn’t it?

Other sources do a better job of answering this question by distinguishing between abbreviations, which usually take a full stop, and contractions, which don’t. Here’s the difference between them:

An ABBREVIATION is a shortened form of a word that does NOT  include the full word’s final letter. Abbreviations should be  followed by a full stop.

A CONTRACTION is a shortened form of a word that DOES include the full word’s final letter. Contractions should not be followed by a full stop.

Here are some examples of abbreviations. Notice that they all omit the final letter of the full word and receive a full stop in its place:

Tues.   Tuesday            approx.   approximately

doz.    dozen              Aug.      August

Prof.   Professor          Aust.     Australia

a.m.    anti meridian      p.m.      post meridian

i.e.    id est             e.g.      exempli gratia

Note that Latin examples like “e.g.” are two separate abbreviations: “e.” for “exempli” and “g.” for “gratia”. There are thus two full stops. Alternatives such as “eg.” or “eg” are not consistent with our principle of following each abbreviation with a full stop.

Here are some examples of contractions. Notice that they all include the final letter of the full word and are not followed by a full stop:

Rd      Road               govt     government

dept    department         ft       feet

Mr      Mister             mfg      manufacturing

Dr      Doctor             Mme      Madame

Pty     Proprietary        Ltd      Limited

Not everyone follows the guidelines presented in this article, although they are increasingly common. Still, in my view, distinguishing between abbreviations and contractions in this way is better than relying on the ambiguous definition quoted earlier that expects you to guess what “often followed by a period” means.

I hope you find this useful.


You’ll find many more helpful tips like these in Tim North’s much applauded range of e-books. More information is available on his web site, and all books come with a money-back guarantee.