Pronunciation: (dē-ak'tu-vāt"), [key]
—v., -vat•ed, -vat•ing.
1. to cause to be inactive; remove the effectiveness of.
2. to demobilize or disband (a military unit).
3. to render (a bomb, shell, or the like) inoperative, esp. by disconnecting, removing, or otherwise interfering with the action of the fuze.
4. Chem.to render (a chemical, enzyme, catalyst, etc.) inactive.
Physical Chem.to lose radioactivity.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.