- abbreviationsThere are several kinds of abbreviations: shortenings, contractions, initialisms, and acronyms.1. Shortenings of words, though formerly condemned by literary figures such as Addison and Pope (18c), are now a common convention, with varying degrees of formality (ad = advertisement, bike = bicycle, pub = public house, rhino = rhinoceros, telly = television). Some are the usual forms, with the original forms now regarded as formal or technical (bus = omnibus, fridge = refrigerator, gym = gymnasium, turps = turpentine, zoo = zoological garden).2. Contractions are a type of shortening in which letters from the middle of the word are omitted (Dr = doctor, St = saint) and are sometimes marked as omitted by use of an apostrophe (can't = cannot, we've = we have).3. Initialisms are abbreviations consisting of a sequence of the initial letters of words that are pronounced as separate letters: a.m., BBC, DfES [= Department for Education and Skills, in the UK], HIV, MP, UN. Practice varies as to including full points between the letters; the style recommended here is not to include them when all the initials are capitals and in some other cases. When the form has a plural, this is formed by adding an -s, now normally without an apostrophe (e.g. MPs rather than MP's). Possessives are formed in the usual way (e.g. MP's singular, MPs' plural).4. Acronyms are initialisms that have gone one stage further and acquired the status of words, being pronounced and treated grammatically as such (Aids, laser, NATO, PIN [= personal identification number], radar). In some cases the original expansions have become irrelevant, as with laser and radar. (See more fully at acronym.)
Modern English usage. 2014.