Acronym vs. Initialism — What's the Difference?

An acronym is a word or name formed from the initial components of a longer name or phrase, usually using individual initial letters, as in NATO (North Atlantic Treaty Organization) or EU (European Union), but sometimes using syllables, as in Benelux (Belgium, Netherlands and Luxembourg), or a mixture of the two, as in radar (RAdio Detection And Ranging). Similarly, acronyms are sometimes pronounced as words, as in NASA or UNESCO, sometimes as the individual letters, as in FBI or ATM, or a mixture of the two, as in JPEG or IUPAC. The broader sense of acronym inclusive of terms pronounced as the individual letters (such as "TNT") is sometimes criticized, but it is the term's original meaning and is in common use.

An abbreviation consisting of the first letter or letters of words in a phrase (for example, IRS for Internal Revenue Service), syllables or components of a word (TNT for trinitrotoluene), or a combination of words and syllables (ESP for extrasensory perception) and pronounced by spelling out the letters one by one rather than as a solid word.

An abbreviation formed from the initial letters of other words and pronounced as a word (e.g. ASCII, NASA).

(linguistics) A term formed from the initial letters of several words or parts of words, which is itself pronounced letter by letter.

A word formed by combining the initial letters of a multipart name, such as NATO from North Atlantic Treaty Organization or by combining the initial letters or parts of a series of words, such as radar from radio detecting and ranging.

(linguistics) The process of forming words or terms using initial letters of other words.

Usage Problem An initialism.

(linguistics) An abbreviation formed by the initial letters of other words, sometimes exclusively such abbreviations when pronounced as a word (as "laser") rather than as individual letters (initialisms such as "TNT").

(linguistics) An abbreviation formed by the beginning letters or syllables of other words (as "Benelux").

To form into an acronym.

A word formed from the initial letters of a multi-word name