(This entry from the Jargon File, which later became the Hackers' Dictionary, originally dates from the mid-80s. The first versions of the Jargon File didn't have an entry for Lisp, because it was assumed that every hacker knew what it was.)

:LISP: /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}. 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 {crock}s. When the {Right Thing} has already been done once, there is no justification for {bogosity} in newer languages.