ice

ice n.  [coined by Usenetter Tom Maddox, popularized by
   William Gibson's cyberpunk SF novels: a contrived acronym for
   `Intrusion Countermeasure Electronics'] Security software (in
   Gibson's novels, software that responds to intrusion by attempting
   to literally kill the intruder).  Also, `icebreaker': a program
   designed for cracking security on a system.

   Neither term is in serious use yet as of mid-1993, but many hackers
   find the metaphor attractive, and each may develop a denotation in
   the future. In the meantime, the speculative usage could be
   confused with `ICE', an acronym for "in-circuit emulator".