Abbreviation (from Latin brevis "short") is strictly a shortening, but more particularly, an abbreviation is a letter or group of letters, taken from a word or words, and employed to represent them for the sake of brevity.
In modern English there are several conventions for abbreviations and the choice may be confusing. The only rule universally accepted is that one should be consistent, and to this end publishers express their preferences in a style guide.
Questions which arise include the following:
- Use of upper or lower case letters. If the original word was capitalised, then the first letter of its abbreviation should retain the capital, e.g., Lev. for Leviticus. When abbreviating words spelt with lower case letters, there is no consistent rule.
- Use of periods (full stops) and spaces, e.g. when abbreviating United States, should one write US, U.S. or U. S.? In American English the period is usually added if the abbreviation may be interpreted as a word, though some American writers do not use a period here. There is no stop/period between letters of the same word, e.g., St. and not S.t. for Saint.
- Many British publications and websites (notably the BBC) follow these guidelines:
- If the abbreviation retains the last letter of the original (as, for example "Mister"), the period is not included: Mr John Smith.
- If the abbreviation does not have the last letter of the original, the period is included. "exempli gratia" is abbreviated as "e.g." (though many British writers would use "eg").
- If used to refer to a country or a group like the United States or United Nations, the period is not included: US and UN respectively.
Acronyms are sometimes referred to with only the first letter of the abbreviation capitalised. For instance, the North Atlantic Treaty Organization can be abbreviated as Nato, and Severe Acute Respiratory Syndrome as Sars. Initialisms (which are similar to acronyms but which are not pronounced as words) are always written in capitals, for instance the British Broadcasting Corporation is abbreviated to BBC, never Bbc.
- Plurals are often formed by doubling up the last letter of the abbreviation. Most of these deal with writing and publishing: MS=manuscript, MSS=manuscripts; l=line, ll=lines; p=page, pp=pages; s=section, ss=sections). This form, derived from Latin is used in Europe in many places: dd=didots. "The following (lines or pages)" is denoted by ff. One example that does not concern printing is hh=hands.
- A doubled letter also appears in abbreviations of some Welsh names, as the Welsh consider a double l a separate sound: "Ll. George" for Lloyd George.
- Whether to add an apostrophe for a plural where the plural is not formed by doubling up the last letter: should one write CDs or CD's? The apostrophe is not needed grammatically but sometimes is added to make it clear that the s is not part of the abbreviation.
After the Second World War, the British greatly reduced their use of the full stop and other punctuations after abbreviations in at least semi-formal writing, while the Americans more readily kept its use until more recently, and still maintain it more than Britons. The classic example, considered by their American counterparts quite curious, was the maintenance of the internal comma in that for the British organization of secret agents called 'Special Operations, Executive' - specifically, S.O.,E. - which you will not find in histories written after about 1960.
But before that, many Britons were more scrupulous at maintaining the French form. In French, the period only follows an abbreviation if the last letter in the abbreviation is not the last letter of its antecedent: M. is the abbreviation for monsieur while Mme is that for Madame and Mademoiselle yields Mlle as its own abbreviation. Like many other cross-channel linguistic acquisitions, many Britons readily took this up and followed this rule themselves, while the Americans took a more simplistic rule and applied it rigorously.
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