This article describes three-letter acronyms. For other uses of the term TLA, see TLA (disambiguation).

TLA (Three-Letter Acronym) is the most popular type of acronym in computing and telecom terminology and Internet slang, and is also very common in general language. There is some disagreement about whether abbreviations like TLA actually constitute acronyms (see acronym and initialism), and this has led to the increasing use of the word abbreviation as opposed to acronym in expanding the term. However, "three-letter acronym" is the older and more frequently cited term.



"TLA" is a TLA itself; the term was almost certainly coined with a certain degree of self-referential humor in mind. Likewise, a four-letter abbreviation is sometimes known as a FLAB (Four Letter ABbreviation), an ETLA or XTLA (Extended TLA), an LFLA (Longer Four Letter Abbreviation) or a TLA/E (TLA/Extended) - although all these are far less common than TLA. In the same vein, VLFLA is a Very Long Five Letter Abbreviation and DETLA is a Doubly-Extended Three Letter Abbreviation.

TLAs became common in the United States during the New Deal of President Franklin D. Roosevelt (who is frequently referred to as FDR). Terms from this period included NRA for National Recovery Administration, CCC for the Civilian Conservation Corps, and TVA for the Tennessee Valley Authority. Detractors of President Roosevelt's policies called the new agencies "alphabet soup."

According to, "TLA" (the eponymous TLA) was coined by Jeff Kelley who worked at the time at IBM, a company whose name itself was a TLA. Jeff Kelley (a.k.a. John F. Kelley, Ph.D., CPE) reports vaguely recalling that the date on which he coined the term was around 1985.


Using only upper-case letters, there are 26³ = 17576 possible three-letter abbreviations, and probably most of them are already used in some context. If numbers, special characters, or case-sensitivity are allowed, even more TLAs can be created.

Many TLAs have more than one meaning: TLA itself is also a TLA for the Theater of the Living Arts ( There are many TLAs with more than 10 meanings (for example, SDI has at least 36 meanings in the English language). Furthermore, many abbreviations have more than one expansion with the same meaning. For example GCC was first 'GNU C Compiler', and later 'GNU Compiler Collection'. (See also backronym.)

In the MS-DOS operating system for personal computers, because only three-letter file extensions (usually denoting the file type) were allowed, many longer abbreviations were shortened to three letters (for example JPEG to JPG, HTML to HTM), and many of these are still used. DOS itself is a TLA for 'Disk Operating System' as well.

Many abbreviations, some of them TLAs, come from the shortened names of Usenet groups. For example, PRA for pl.rec.anime, or AFU for alt.folklore.urban.


TLAs are typically pronounced as initialisms (i.e., Tee Ell Ay) and written in all capital letters. Some, however are acronyms, and are pronouned as words (e.g., RAM). TLAs are pluralized by adding s (as in TLAs). The possessive is formed by adding apostrophe s (as in TLA's). Increasing numbers of TLAs, and other abbreviations, are showing Redundant Acronym Syndrome, in which usually the last of the abbreviated words is added to the TLA (for example, ATM machine, PIN number, HIV virus). Purists recommend avoiding RAS syndrome, especially in formal writing such as technical writing.

Common categories of TLAs

A significant number of TLAs come from various codes:

Lists of TLAs

See also

fr:Sigles de trois lettres it:TLA sl:Tričrkovna kratica sv:TLA


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