Abbreviations and Acronyms

An abbreviation is a shortened form of a word, e.g. Mr for Mister. An acronym is a form of abbreviation which is usually produced from the initial letters of words e.g. lidar from light detection and ranging. An abbreviation also has to be distinguished from a symbol e.g. using + for plus and from contractions where letters are omitted e.g. fo'csle.

General

Only use an abbreviation or acronym if it is used more than twice in the text. Spell out the abbreviation or acronym the first time it is used and follow it by the shortenned form in parentheses. Do this both in the text and in the abstract. So

• quasi-biennial oscillation (QBO) not QBO (quasi-biennial oscillation)

Abbreviations

The full point is usually used after abbreviations but not for:

• an abbreviation for the name of a unit of measurement (cm not cm.)
• Mr, Mrs, Messrs, Dr, Mt, Pt, St

The abbreviations 'e.g.' and 'i.e.' are never followed by a comma.

Acronyms

An acronym is an abbreviation formed from letters in a phrase. The two principal forms of acronym are:

• those that are pronounced as a word,

  NATO, North Atlantic Treaty Organization

  At some point this type of acronym metamorphoses into a standard word (e.g. radar) and no longer needs defining.

• those that are pronounced as letters. Note that a period can be used to indicate missing letters.

  G.B.

  However this rule is not strictly adhered to so we have

  WMO, World Meteorological Organization

Do not back-capitalise abbreviated phrases to suit an acronym's capitaliation. So

• gross domestic product (GDP) not Gross Domestic Product (GDP)
• general circulation model (GCM) not General Circulation Model (GCM)