Source : WordNet®

logic bomb
     n : a delayed action computer virus; a set of instructions
         surreptitously inserted into a program that are designed
         to execute (or `explode') if a particular condition is
         satisfied; when exploded it may delete or corrupt data,
         or print a spurious message, or have other harmful
         effects; "a disgruntled employee planted a logic bomb"
         [syn: {slag code}]

Source : Free On-Line Dictionary of Computing

logic bomb
     
         Code surreptitiously inserted into an
        application or {operating system} that causes it to perform
        some destructive or security-compromising activity whenever
        specified conditions are met.
     
        Compare {back door}.
     
        [{Jargon File}]
     
        (1996-07-02)