A program that modifies other programs or databases in unauthorised ways; especially one that propagates a virus or Trojan horse. See also worm, mockingbird. The analogy, of course, is with phage viruses in biology.

[Jargon File]

Nearby terms:

phphackerphagephasephase alternating linePhase Encoded

Try this search on Wikipedia, Wiktionary, Google, OneLook.