Three-letter acronym

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A three-letter acronym (TLA), or three-letter abbreviation, is an abbreviation consisting of three letters. These are usually the initial letters of the words of the phrase abbreviated, and are written in capital letters (upper case); three-letter abbreviations such as etc. and Mrs. are not three-letter acronyms, but "TLA" itself is a TLA (an example of an autological abbreviation).

Most three-letter abbreviations are not, strictly, acronyms, but rather initialisms: all the letters are pronounced as the names of letters, as in APA /ˌpˈ/ AY-pee-AY. Some are true acronyms, pronounced as a word: as with computed axial tomography, for example, CAT is almost always pronounced as the animal's name (/kæt/) in "CAT scan". Even the initialisms are however considered three-letter acronyms, because that term appeared first in widespread use, and is overwhelmingly popular today.


History and origins[edit]

The exact phrase three-letter acronym appeared in the sociology literature in 1975.[1] Three-letter acronyms were used as mnemonics in biological sciences, from 1977[2] and their practical advantage was promoted by Weber in 1982.[3] They are used in many other fields, but the term TLA is particularly associated with computing.[4] In 1980, the manual for the Sinclair ZX81 home computer used and explained TLA.[5] The specific generation of three-letter acronyms in computing was mentioned in a JPL report of 1982.[6] In 1988, in a paper titled "On the Cruelty of Really Teaching Computing Science", eminent computer scientist Edsger W. Dijkstra wrote (disparagingly), "No endeavour is respectable these days without a TLA"[7] By 1992 it was in a Microsoft handbook.[8]


The number of possible three-letter abbreviations using the 26 letters of the alphabet from A to Z (AAA, AAB ... to ZZY, ZZZ) is 26 × 26 × 26 = 17,576. An additional 26 × 26 × 10 = 6760 can be produced for each single position allowed to be a digit 0-9, such as 2FA, P2P, or WW2, giving a total of 37,856 such three-character strings.

In standard English, WWW is the TLA whose pronunciation requires the most syllables—typically nine. The usefulness of TLAs typically comes from its being quicker to say than the phrase it represents; however saying 'WWW' in English requires three times as many syllables as the phrase it is meant to abbreviate (World Wide Web). "WWW" is sometimes abbreviated to "dubdubdub" in speech.[9]

References in popular culture[edit]

  • As early as 1967, the musical Hair included the song "Initials", whose final verse consisted only of TLAs, viz: "LBJ IRT USA LSD. LSD LBJ FBI CIA. FBI CIA LSD LBJ."[10]
  • In 1999, the author Douglas Adams remarked: "The World Wide Web is the only thing I know of whose shortened form takes three times longer to say than what it's short for."[11]
  • According to the Jargon File, a journalist once asked hacker Paul Boutin what he thought the biggest problem in computing in the 1990s would be. Paul's straight-faced response was: "There are only 17,000 [sic] three-letter acronyms."[12]
  • The Jargon File also mentions the abbreviation "ETLA" for "extended three-letter acronym" to refer to four-letter acronyms/abbreviations. "Extended three-letter acronym" is sometimes abbreviated to "XTLA".[12]
  • In the comic strip Dilbert the title character is working on a project called TTP.[13] The initials stand for 'The TTP Project.' This is also an example of a recursive acronym.

See also[edit]


  1. ^ Levy, M. J. (1975). "Review of The Logic of Social Systems". American Journal of Sociology. 81 (3): 658. doi:10.1086/226119. JSTOR 2777655. The acronyms DSE and DNA have something in common: each is a three-letter acronym.
  2. ^ Seavey, S. R.; Raven, P. H. (1977). "Chromosomal Differentiation and the Sources of the South American Species of Epilobium (Onagraceae)". Journal of Biogeography. 4 (1): 57. doi:10.2307/3038128. JSTOR 3038128. All taxa indicated by three-letter acronyms with strains indicated by a fourth letter if necessary.
  3. ^ Weber, W. A. (1982). "Mnemonic Three-Letter Acronyms for the Families of Vascular Plants: A Device for More Effective Herbarium Curation". Taxon. 31 (1): 74–88. doi:10.2307/1220592. JSTOR 1220592.
  4. ^ Nilsen, K. D.; Nilsen, A. P. (1995). "Literary Metaphors and Other Linguistic Innovations in Computer Language". The English Journal. 84 (6): 65–71. doi:10.2307/820897. JSTOR 820897.
  5. ^ Steven Vickers ZX81 Basic Programming, Sinclair Research Limited, page 161 "As you can see, everything has a three letter abbreviation (TLA)."
  6. ^ TDA Progress Report R. Hull (1982) An Introduction to the new Productivity Information Management System page 176
  7. ^ On the cruelty of really teaching computer science
  8. ^ Dan Gookin (1992) The Microsoft Guide to Optimizing Windows page 211
  9. ^ "DigiSpeak: A Glossary of the New Lingo". bryn mawr alumnae bulletin. Bryn Mawr College Alumnae Association. May 2011. Retrieved August 14, 2016.
  10. ^ Video on YouTube
  11. ^ Douglas Adams, The Independent on Sunday, 1999
  12. ^ a b TLA,
  13. ^ "Dilbert Comic Strip on 1994-05-18 | Dilbert by Scott Adams". 1994-05-18. Retrieved 2022-04-11.