What is the Full Form of GNU ?

GNU - GNU's Not Unix!

The GNU some times also written as GNU General Public License, is intended to guarantee the freedom to develop and share software for free, for all its users. It was started as a project by Richard Stallman in 1983 with a focus on providing Free Software. It is named as a Unix-like computer operating system, because its design is similar to Unix but contains no Unix Code. It is available in multiple language(s) with platform supported is x86 & x86-64. Today, it is widely used on other operating systems such as BSD variants, Mac OS X and Solaris.

Origin of GNU
The Project "GNU's Not Unix!" was publicly announced on September 27, 1983 by Richard Stallman and the development began on January 5, 1984. The goal of the project was to develop a free software operating system.