From The Free On-line Dictionary of Computing (19 January 2023):
GNU
<body, project> /g*noo/ 1. A recursive acronym:
"GNU's Not Unix!". The Free Software Foundation's project
to provide a freely distributable replacement for Unix. The
GNU Manifesto was published in the March 1985 issue of
Dr. Dobb's Journal but the GNU project started a year and a
half earlier when Richard Stallman was trying to get funding
to work on his freely distributable editor, Emacs.
Emacs and the GNU C compiler, gcc, two tools designed
for this project, have become very popular. GNU software is
available from many GNU archive sites.
See also Hurd.
2. <person> John Gilmore.
(1997-04-12)