For example, AIM stands for AOL Instant Messenger, and AOL stands for American OnLine. This isn’t quite the same thing as a recursive acronym, which refers to itself. Maybe the term is nested acronym?

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    Please check standard dictionaries for the default usage of 'acronym' (versus 'initialism'). Using this, BBC is an initialism rather than an acronym, while NASA (see Kennedy Space Center.com) is an acronym. // AOL is obviously an initialism; how is AIM pronounced? Commented Apr 9, 2022 at 15:21
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    Unsure if this is an actual answer. I have come across TLA. Collins says it is three-letter abbreviation or three-letter acronym. Commented Apr 10, 2022 at 13:05
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    @WeatherVane Don't forget about the ETLA. That's an extended three-letter abbreviation. Because always there shall be three letters in your abbreviations. Four shalt thou not count, neither count thou two, excepting that thou then proceed to three. Five is right out. Commented Apr 10, 2022 at 19:15
  • @EdwinAshworth: Not sure it's terribly relevant, but AIM is an acronym, not an initialism. At least, it was in my neck of the woods when it was a relevant program.
    – MichaelS
    Commented Apr 11, 2022 at 4:51
  • @MichaelS 'What’s the term for an acronym that refers to another acronym? ... For example, AIM ...' would not be using the standard default definition (and the one used on ELU) for 'acronym' were AIM not pronounced as a word. Mixing stipulative definitions willy-nilly is confusing and unhelpful. Mind you, 'nested acronym' muddies the waters perhaps irretrievably. Commented Apr 11, 2022 at 13:10

2 Answers 2


You're correct, it is in fact a nested acronym:

nested acronym: an acronym where one of the letters represents another acronym. e.g. AIM (AOL Instant Messenger)

You're also correct that it's not a recursive acronym, of which GNU (GNU's Not Unix) is the most infamous example:

recursive acronym: an acronym which refers to itself in the expression for which it stands. e.g. VISA standing for Visa International Service Association

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    My favorite is the mutually recursive acronym in GNU Hurd, where "Hurd" stands for HIRD of Unix-Replacing Daemons, where "HIRD" stands for HURD of Interfaces Representing Depth. Commented Apr 9, 2022 at 9:49
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    @JörgWMittag Wooof! That is evil! :-) Commented Apr 9, 2022 at 14:16
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    my favorite recursive acronym would have to be PHP, which stands for "PHP Hypertext Preprocessor"
    – RWolfe
    Commented Apr 10, 2022 at 5:23
  • I like GNU itself, the recursive "GNU is not Unix". Commented Apr 10, 2022 at 13:08
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    "VISA standing for Visa International Service Association" unclear if "Visa" here refers to VISA or visa or what. Commented Apr 11, 2022 at 9:52

It is also called a macronym or a multi-layered acronym, although the term "nested acronym" is more common:

A macronym, or nested acronym, is an acronym in which one or more letters stand for acronyms (or abbreviations) themselves. The word "macronym" is a portmanteau of "macro-" and "acronym".

Some examples of macronyms are:

  • XHR stands for "XML HTTP Request", in which "XML" is "Extensible Markup Language", and HTTP stands for "HyperText Transfer Protocol"
  • POWER stands for "Performance Optimization With Enhanced RISC", in which "RISC" stands for "Reduced Instruction Set Computing"
  • VHDL stands for "VHSIC Hardware Description Language", in which "VHSIC" stands for "Very High Speed Integrated Circuit"
  • XSD stands for "XML Schema Definition", in which "XML" stands for "Extensible Markup Language"
  • AIM stands for "AOL Instant Messenger", in which "AOL" originally stood for "America Online"
  • HASP stood for "Houston Automatic Spooling Priority", but "spooling" itself was an acronym: "simultaneous peripheral operations on-line"
  • VORTAC stands for "VOR+TACAN", in which "VOR" is "VHF omnidirectional range" (where VHF = Very High Frequency radio) and "TAC" is short for TACAN, which stands for "Tactical Air Navigation"

(From Wikipedia)

Here's a deeply nested acronym (for fun): VITAL, which expands to "VHDL Initiative Towards ASIC Libraries", which further expands to "VHSIC Hardware Description Language Initiative Towards Application-Specific Integrated Circuit Libraries", which further expands to "Very High Speed Integrated Circuit Hardware Description Language Initiative Towards Application-Specific Integrated Circuit Libraries". That's 15 words long when fully expanded!

  • VORTAC seems irregular because TAC expands to TACAN which is an abbreviation which itself expands to something that itself is more of an abbreviation than an acronym or initialism.
    – Michael
    Commented Apr 11, 2022 at 14:32

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