kernel kernal (Note: NOT "kernal"). 1. <operating system> The essential part of {Unix} or other {operating systems}, responsible for resource allocation, low-level hardware interfaces, security etc. See also {microkernel}. 2. <language> An essential subset of a programming language, in terms of which other constructs are (or could be) defined. Also known as a {core} language. (1996-06-07)