GNU

Etymology
as a recursive acronym for “GNU's Not Unix”, following convention of naming programs similar to or inspired by existing programs as “(New Name) Is Not (Old Name)”; compare.

Specifically influenced by lack of English words of form ?nu (“?NU is Not Unix”), that is the alphabetically first (and in fact only) English word of the form ?nu (“?’s Not Unix”), that gnu was perceived as a humorous word, and the existence of the song .

Proper noun

 * 1) The Free Software Foundation's project to develop a free UNIX-like operating system, including the legal framework, such as the source code and documentation licenses.

Proper noun

 * 1)  GNU