An abbreviation (from Latin brevis, meaning short) is a shortened form of a word or phrase. It consists of a group of letters taken from the word or phrase. For example, the word abbreviation can itself be represented by the abbreviation abbr., abbrv. or abbrev.

In American English, many abbreviations are followed by a period (Dr., Ms.). In contrast, British usage generally favors omitting the period (or full stop) in abbreviations that include the first and last letters of a single word (Dr, Ms).