gnu define
GNU / É¡ n uË / ( listen) is an operating system and an extensive collection of computer software. GNU is composed wholly of free software, most of which is licensed under the GNU Project's own GPL. GNU is a recursive acronym for GNU's Not Unix!, chosen because GNU's design is Unix-like, but differs from Unix by being free software and containing no Unix code. The GNU project includes an operating system kernel, GNU HURD, which was the original focus of the Free Software Foundation (FSF). However, non-GNU kernels, most famously Linux, can also be used with GNU software; as the Hurd kernel is not yet production-ready, this is how the GNU system is usually used.