Initialism of GNU Compiler Collection. It is a collection of compilers for C, C++, Fortran, etc. aiming to be standards-compliant and correct.
"Developers often use gcc as the initialism for GNU Compiler Collection because it serves as a comprehensive suite of compilers designed to adhere strictly to language standards."
GCC began as an acronym for the GNU C Compiler. It is now used as a backronym to stand for the GNU Compiler Collection.