A recursive acronym is an acronym that refers to itself. The term was first used in print in 1979 in Douglas Hofstadter's book Gödel, Escher, Bach: An Eternal Golden Braid, in which Hofstadter invents the acronym GOD, meaning "GOD Over Djinn", to help explain infinite series, and describes it as a recursive acronym. Other references followed, however the concept was used as early as 1968 in John Brunner's science fiction novel Stand on Zanzibar. In the story, the acronym EPT (Education for Particular Task) later morphed into "Eptification for Particular Task".
Recursive acronyms typically form backwardly: either an existing ordinary acronym is given a new explanation of what the letters stand for, or a name is turned into an acronym by giving the letters an explanation of what they stand for, in each case with the first letter standing recursively for the whole acronym.
In computing, an early tradition in the hacker community (especially at MIT) was to choose acronyms and abbreviations that referred humorously to themselves or to other abbreviations. Perhaps the earliest example in this context – from 1960 – is the backronym "Mash Until No Good", which was created to describe Mung, and a while later was revised to "Mung Until No Good". It lived on as a recursive command in the editing language TECO. In 1977 or 1978 came TINT ("TINT Is Not TECO"), an editor for MagicSix written (and named) by Ted Anderson. This inspired the two MIT Lisp Machine editors called EINE ("EINE Is Not Emacs", German for one) and ZWEI ("ZWEI Was EINE Initially", German for two). These were followed by Richard Stallman's GNU (GNU's Not Unix). Many others also include negatives, such as denials that the thing defined is or resembles something else (which the thing defined does in fact resemble or is even derived from), to indicate that, despite the similarities, it was distinct from the program on which it was based.
An earlier example appears in a 1976 textbook on data structures, in which the pseudo-language SPARKS is used to define the algorithms discussed in the text. "SPARKS" is claimed to be a non-acronymic name, but "several cute ideas have been suggested" as expansions of the name. One of the suggestions is "Smart Programmers Are Required to Know SPARKS". (this example is tail recursive)
Some organizations have been named or renamed in this way:
- BWIA — BWIA West Indies Airways (formerly British West Indian Airways)
- FAIR — Fairness and Accuracy in Reporting
- FARM — Farm Animal Rights Movement
- FALE — FALE Association of Locksport Enthusiasts
- GES — GES Exposition Services (formerly Greyhound Exposition Services)
- hEART — hEART the European Association for Research in Transportation
- Heil — Heil Environmental Industries Limited, maker of garbage trucks
- VISA — Visa International Service Association
- WAT — WAT Automotive Technologies
- Allegro — Allegro Low LEvel Game ROutines (early versions for Atari ST were called "Atari Low Level Game Routines")
- AGFA — Always Go For AGFA
- ANX — ANX's Not XNA
- AROS — AROS Research Operating System (originally Amiga Research Operating System)
- ATI — ATI Technologies Inc.
- BAMF — BAMF Application Matching Framework
- BIRD — BIRD Internet Routing Daemon
- BOSH — Bosh Outer Shell
- CAVE — CAVE Automatic Virtual Environment
- cURL — Curl URL Request Library
- Darcs — Darcs Advanced Revision Control System
- EINE — EINE Is Not Emacs
- ENAML — ENAML is Not A Markup Language 
- FIJI — FIJI Is Just ImageJ
- FYBMEM — FYBMEM Your Basic Monitor Editor Mechanism
- Giantleap - Giantleap Improves Automation of Non-polluting Transportation with Lifetime Extension of Automotive PEM fuel cells.
- GiNaC — GiNaC is Not a CAS (Computer Algebra System)
- GNU — GNU's Not Unix
- GPE — GPE Palmtop Environment
- gRPC — grpc Remote Procedure Calls
- HIJOS — Hijos por la Identidad y la Justicia contra el Olvido y el Silencio
- HIME — HIME Input Method Editor
- INX — INX's Not X (a UNIX clone)
- JACK — JACK Audio Connection Kit
- JOE — Joe's Own Editor
- KGS — KGS Go Server
- LAME — LAME Ain't an MP3 Encoder
- LIFE — LIFE Is For Ever
- LiVES — LiVES is a Video Editing System
- MEGA — MEGA Encrypted Global Access
- MIATA — MIATA is Always the Answer
- MINT — MINT Is Not TRAC
- MiNT — MiNT is Not TOS (later changed to "MiNT is Now TOS")
- Mung — Mung Until No Good
- Nano — Nano's Another editor
- Nagios — Nagios Ain't Gonna Insist On Sainthood (a reference to the previous name of Nagios, "Netsaint"; agios [αγιος] is the Greek word for "saint")
- NiL — NiL Isn't Liero
- Ninja-ide – Ninja-IDE Is Not Just Another IDE
- NITE — NITE Isn't TECO Either (the 2nd offering from the creator of TINT)
- pacc — pacc: a compiler-compiler
- PHP — PHP: Hypertext Preprocessor (from "Personal Home Page Tools," more frequently referenced as "PHP Tools.")
- PINE — PINE Is Nearly Elm, originally; PINE now officially stands for "Pine Internet News and E-mail"
- PINN — PINN Is Not NOOBS
- PIP — PIP Installs Packages
- PIPER — PIPER Is PIPER Expanded Recursively (Google's internal version control system)
- P.I.P.S. — P.I.P.S. Is POSIX on Symbian
- Qins — Qins is not Slow
- rif — rif is fun (originally Reddit is Fun)
- SPARQL — SPARQL Protocol And RDF Query Language
- TikZ – TikZ ist kein Zeichenprogramm (German; TikZ is not a drawing program)
- TIARA — TIARA is a recursive acronym
- TiLP — TiLP is a Linking Program
- TIP — TIP isn't Pico
- TRESOR – TRESOR Runs Encryption Securely Outside RAM
- UIRA — UIRA Isn't a Recursive Acronym
- WINE — WINE Is Not an Emulator (Originally, Windows Emulator)
- XAMPP — XAMPP Apache MariaDB PHP Perl
- XBMC — XBMC Media Center (originally Xbox Media Center)
- XINU — Xinu Is Not Unix
- XNA — XNA's Not Acronymed
- XNU — X is Not Unix
- YAML — YAML Ain't Markup Language (initially "Yet Another Markup Language")
- ZINC – ZINC Is Not Commercial
- Zinf — Zinf Is Not FreeAmp
- ZOMBIE - Zombie is Optical Measurement of Barcodes by In-situ Expressiona, a technique for analysis of individual cells
- ZWEI — ZWEI Was EINE Initially (“eins” and “zwei” are German for “one” and “two” respectively)
- TTP - a technology project in the Dilbert comic strip. The initials stand for "The TTP Project".
- GRUNGE - defined by Homer Simpson in The Simpsons episode "That '90s Show" as "Guitar Rock Utilizing Nihilist Grunge Energy", another uncommon example of a recursive acronym whose recursive letter is neither the first nor the last letter.
- KOS-MOS - a character from the Xenosaga series of video games. "KOS-MOS" is a recursive acronym meaning "Kosmos Obey Strategical Multiple Operating Systems". It's unclear if it counts as a true recursive acronym, however, as the Kosmos referred to in the acronym may simply be an alternate spelling of cosmos.
Mutually recursive or otherwise special
- The GNU Hurd project is named with a mutually recursive acronym: "Hurd" stands for "Hird of Unix-Replacing Daemons", and "Hird" stands for "Hurd of Interfaces Representing Depth."
- RPM, PHP, XBMC and YAML were originally conventional acronyms which were later redefined recursively. They are examples of, or may be referred to as, backronymization, where the official meaning of an acronym is changed.
- Jini claims the distinction of being the first recursive anti-acronym: 'Jini Is Not Initials'. It might, however, be more properly termed an anti-backronym because the term "Jini" never stood for anything in the first place. The more recent "XNA", on the other hand, was deliberately designed that way.
- Most recursive acronyms are recursive on the first letter, which is therefore an arbitrary choice, often selected for reasons of humour, ease of pronunciation, or consistency with an earlier acronym that used the same letters for different words, such as PHP, which now stands for "PHP: Hypertext Preprocessor", but was originally "Personal Home Page". However YOPY, "Your own personal YOPY" is recursive on the last letter.
- RAS syndrome – Using an acronym followed by one of the words composing that acronym (Redundant Acronym Syndrome syndrome)
- Self-reference – A sentence, idea or formula that refers to itself
- Web Ontology Language – Family of knowledge representation languages, which intentionally uses the acronym "OWL"
- Bilingual tautological expressions – Use of more words than is necessary for clear expression
- Three-letter acronym A three letter acronym that describes three letter acronyms
- "Puzzles and Paradoxes: Infinity in Finite Terms". Retrieved 23 April 2013.
- "WordSpy – Recursive Acronym". Retrieved 18 December 2008.
- The Free Software Movement and the Future of Freedom: The name "GNU", Richard Stallman, March 9th 2006
- Fundamentals Of Data Structures (Ellis Horowitz & Sartaj Sahni, Computer Science Press, 1976)
- "FALE Association of Locksport Enthusiasts". Archived from the original on 22 February 2014. Retrieved 12 February 2014.
- Wiles, Jack; Gudaitis, Terry; Jabbusch, Jennifer; Rogers, Russ; Lowther, Sean (2 January 2012). FALE Association of Locksport Enthusiasts. ISBN 9781597496650. Retrieved 12 February 2014.
- Stenberg, Daniel (20 March 2015). "curl, 17 years old today". daniel.haxx.se. Retrieved 20 March 2015.
- "HIME Input Method Editor". Retrieved 8 May 2019.
- "About LAME". Retrieved 20 February 2016.
- "MEGA". Retrieved 19 January 2013.
- "The Jargon File: Mung". Retrieved 15 October 2007.
- "pacc: a compiler-compiler". Archived from the original on 18 July 2012. Retrieved 14 May 2012.
- "History of PHP". php.net.
- "What Pine Really Stands For". Archived from the original on 7 June 2011. Retrieved 6 March 2007.
- QINS website
- "Reddit is Fun now called 'rif is fun for reddit' due to licensing issues". Android Police. 7 January 2020. Retrieved 4 March 2020.
- .EXE magazine, November 1996
- "FAQ – The Official Wine Wiki". Retrieved 16 January 2009.
- "Wine architecture". Wine HQ. Retrieved 16 June 2012.
- "Porting UNIX/Linux Applications to Mac OS X: Glossary". Apple Computer. 2005. Retrieved 7 June 2017.
- Askary, A.; Sanchez-Guardado, L.; Linton, J. M.; Chadly, D. M.; Budde, M. W.; Cai, L.; Lois, C.; Elowitz, M. B. (18 November 2019). "In situ readout of DNA barcodes and single base edits facilitated by in vitro transcription". Nature Biotechnology. 38 (1): 66–75. doi:10.1038/s41587-019-0299-4. PMC 6954335. PMID 31740838.
- "Dilbert's TTP Project". Dilbert. Retrieved 9 July 2018.
- FAQ for JINI-USERS Mailing List, Retrieved 18 November 2013
- Introduction to The Jini Specification, Arnold et al, Pearson, 1999, ISBN 0201616343
- This article is based in part on the Jargon File, which is in the public domain.
- The dictionary definition of recursive acronym at Wiktionary