What is the difference between these initialisms‎ vs acronyms vs abbreviations?
As I understand from SO:

initialisms‎ are like BOA,USA(i.e. letter by letter).
acronyms are like NASA, AIDS(i.e. words).

than what is abbreviations?

  • 4
    In ordinary speech, most people don't distinguish between "initialism" and "acronym". Most people say "acronym" for both, and most people have never even heard the word "initialism". The distinction is rather fussy, mainly of interest to grammarians.
    – Ben Kovitz
    May 19, 2015 at 19:01
  • Related question on ELU: english.stackexchange.com/questions/3755/difference-between-an-acronym-and-abbreviation.
    – pyobum
    Dec 15, 2015 at 18:15

1 Answer 1


An abbreviation shortens one word or a short sequence of words to one or a few letters. A few random examples:

  • misc. for miscellaneous (abbreviation)
  • Dr for doctor (contraction)
  • HTML for HyperText Markup Language (initialism)
  • sonar for sound navigation and ranging (acronym)
  • etc. for et cetera
  • Sat. for Saturday
  • LOL for laughing out loud
  • John F. Kennedy (or JFK) for John Fitzgerald Kennedy
  • ...

As you can see, in the wider definition abbreviations encompasses contractions ("dropping letters from the middle of a word", acronyms and initialisms (using the first letter(s) of a multi-word phrase) and abbreviations in the stricter sense, which are defined as "dropping letters from the end of a word".

  • So what's the difference between acronyms and initialisms?
    – Kreiri
    May 19, 2015 at 13:03
  • @Kreiri: Initialisms use the first letters and pronounce them letter-by-letter: Chief Executive Officer shortens to CEO and reads "ce-e-oh". Acronyms use sometimes more than one letter of each word and form new "words", see "sonar" in the answer above. Also note that those two are not mutually exclusive: The ICE train is in the US spoken like the frozen water but originally stands for "Inter City Express".
    – Stephie
    May 19, 2015 at 15:27
  • The rule for an an initialism becoming an acronym is one of convenience and familiarity. Ice is a familiar word, and ICE slips easily into acronym. Likewise, long initialisms are extremely rare, and almost invariably are rejected in favor of acronyms. The cutoff point seems to be about 3 letters. While the FTC (Federal Trade Commission) is pretty well fixed, the President of the United States is (when abbreviated for convenience) POTUS, pronounced "poe - tuss". Jul 18, 2015 at 16:36
  • My understanding has always been that an acronym must be pronouncable, whereas an initialise is pronounced letter by letter. Nov 15, 2015 at 21:53

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