Pronunciation: (ded'līn"), [key]
1. the time by which something must be finished or submitted; the latest time for finishing something: a five o'clock deadline.
2. a line or limit that must not be passed.
3. (formerly) a boundary around a military prison beyond which a prisoner could not venture without risk of being shot by the guards.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.