Linux's First Free Operating System Is a Bit Nutty

This page is the CodyCross answer for the clue below from Underground Worlds, Group 2170, Puzzle 1 (Crystals and Gems).

Question is: Linux's First Free Operating System Is a Bit Nutty

and the answer is: KERNEL

Word Meaning:

KERNEL — The core, center, or essence of an object or system.

Definitions from Wiktionary.

Linux's First Free Operating System Is A Bit Nutty - Underground Worlds CodyCross Answers | CodyCross Solutions