Source : Webster's Revised Unabridged Dictionary (1913)

Nil \Nil\ [See {Nill}, v. t.]
   Will not. [Obs.] --Chaucer.

Nil \Nil\, n. & a. [L., a contr. of nihil.]
   Nothing; of no account; worthless; -- a term often used for
   canceling, in accounts or bookkeeping. --A. J. Ellis.

Source : WordNet®

nil
     n : a quantity of no importance; "it looked like nothing I had
         ever seen before"; "reduced to nil all the work we had
         done"; "we racked up a pathetic goose egg"; "it was all
         for naught"; "I didn't hear zilch about it" [syn: {nothing},
          {nix}, {nada}, {null}, {aught}, {cipher}, {cypher}, {goose
         egg}, {naught}, {zero}, {zilch}, {zip}]

Source : Free On-Line Dictionary of Computing

NIL
     
        /nil/ 1. New Implementation of Lisp.  A language intended to
        be the successor of {MacLisp}.  A large {Lisp}, implemented
        mostly in {VAX} {assembly language}.  A forerunner of {Common
        LISP}.
     
        ["NIL: A Perspective", Jon L. White, MACSYMA Users' Conf Proc,
        1979].
     
        2. Network Implementation Language.  Strom & Yemini, TJWRC,
        IBM.  Implementation of complex networking protocols in a
        modular fashion.
     
        ["NIL: An Integrated Language and System for Distributed
        Programming", R. Strom et al, SIGPLAN Notices 18(6):73-82
        (June 1983)].
     
        3. Empty list or False.  In {Lisp}, the empty list (or "nil
        list") is used to represent the {Boolean} value False.  This
        is possible because {Lisp} is not typed.  True is represented
        by the special {atom} "t".
     
        4. Spoken in reply to a question, particularly one asked using
        the "-P" convention it means "No".  Most hackers assume this
        derives simply from LISP, but NIL meaning "no" was
        well-established among radio hams decades before LISP existed.
        The historical connection between early hackerdom and the ham
        radio world was strong enough that this may have been an
        influence.
     
        [{Jargon File}]