Three-letter acronym

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; 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 originsEdit

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 if the third position is allowed to be a digit 0-9, giving a total of 24,336.

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 cultureEdit

  • 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."
  • 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."[10]
  • 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."
  • 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".

See alsoEdit


  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. 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. ^ Douglas Adams, The Independent on Sunday, 1999