1. A high-level programming language, often used for artificial intelligence research, that makes no distinction between the program and the data. This language is considered ideal for manupulating text. One of the oldest programming labguages still in use, LISP is a declarative language; the programer composes lists that declare the relationships among symbolic values. Lists are the fundamental data structure of LISP, and the program performs computations on the symbolic values expressed in those lists. Like other public domain programming languages, however, a numbver of mutually unintelligible versions of LISP exist. A standardised, fully configured, and widely accepted version is Common LISP. See interpreter. From QUECID

2. LISt Processing language - Artificial Intelligence's mother tongue, a symbolic, functional, recursive language based on the ideas of lambda-calculus, variable-length lists and trees as fundamental data types and the interpretation of code as data and vice-vers. From Linux Guide @FirstLinux

3. n. [from `LISt Processing language', but mythically from `Lots of Irritating Superfluous Parentheses'] AI's mother tongue, a language based on the ideas of (a) variable-length lists and trees as fundamental data types, and (b) the interpretation of code as data and vice-versa. Invented by John McCarthy at MIT in the late 1950s, it is actually older than any other HLL still in use except FORTRAN. Accordingly, it has undergone considerable adaptive radiation over the years; modern variants are quite different in detail from the original LISP 1.5. The dominant HLL among hackers until the early 1980s, LISP now shares the throne with C. Its partisans claim it is the only language that is truly beautiful. See languages of choice. All LISP functions and programs are expressions that return values; this, together with the high memory utilization of LISPs, gave rise to Alan Perlis's famous quip (itself a take on an Oscar Wilde quote) that "LISP programmers know the value of everything and the cost of nothing". One significant application for LISP has been as a proof by example that most newer languages, such as COBOL and Ada, are full of unnecessary crocks. When the Right Thing has already been done once, there is no justification for bogosity in newer languages. From Jargon Dictionary