full stop

full stop

1. The principal use of the full stop (also called point, full point, and period) is to mark the end of a sentence that is a statement (as in this sentence). This applies to sentences when they are not complete statements or contain ellipsis (see sentence), as in the opening of Dickens's Bleak House (1852–3): London. Michaelmas term lately over, and the Lord Chancellor sitting in Lincoln's Hall. Implacable November weather. If the sentence is a question or exclamation, the mark used is the question mark or exclamation mark, which include a full stop in their forms.

2. The full stop is also used to mark abbreviations and contractions, although this use is diminishing, partly as a matter of printing style and partly because many abbreviations have become more familiar and no longer need identification. The distinction between abbreviations (e.g. I.o.W. = Isle of Wight) and contractions (e.g. Dr = Doctor), though arguably a useful one, has been rapidly eroded by this process, so that shortenings of various kinds are printed and written without full stops, e.g. BBC, etc, ie, IoW, Mr, Ms, pm (= post meridiem), St (= Saint or Street), etc. The style recommended here involves dropping full stops in initialisms that are all capital letters (e.g. BBC, NNW = north-north-west, TUC), in many contractions (Dr, Mr, etc.), and in acronyms that are pronounced as words (e.g. Anzac, Nato), but retaining them in lower-case initialisms such as a.m., e.g., and i.e. and in shortened words such as Oct. (= October), Tues. (= Tuesday), and Visc. (= Viscount). In mixed styles the tendency now is to omit points, as in DPhil, M. Litt, and GeV (= gigaelectronvolt). The important point, however, is to achieve consistency within a particular piece of writing or printing. Some shortenings have a greater need of full stops to avoid possible ambiguity with other words in some contexts, e.g. a.m. (= ante meridiem), no. (= number).

3. If an abbreviation with a full stop comes at the end of a sentence, another full stop is not added when the full stop of the abbreviation is the last character: Bring your own pens, pencils, rulers, etc. but Bring your own things (pens, pencils, rulers, etc.).

4. Full stops are routinely used between units of money (£11.99, $27.50), before decimals (10.5%), and between hours and minutes (10.30 a.m.; AmE 10:30 a.m.).