v. t. To make active. [ Obs. ] [ 1913 Webster ]

adj. 1. (Sewage treatment) treated with aeration and bacteria to aid decomposition; -- of sewage [ WordNet 1.5 ]

3. (Physics) made reactive or more reactive; -- of e.g. a molecule
Syn. -- activated, excited [ WordNet 1.5 ]

4. rendered active; -- as e.g. radioactive or luminescent or photosensitive or conductive
Syn. -- activated [ WordNet 1.5 ]

5. (Military) set up and placed on active assignment a newly activated unit
Syn. -- activated [ WordNet 1.5 ]

v. t. 1. To make inactive; to render ineffective; as, to deactivate a bomb; to deactivate a machine; to deactivate the alarm. The deactivation of a machine or device is usually a reversible process; switching off an electrical device may be referred to as deactivation. To render an enzyme or catalyst ineffective is more commonly referred to as to inactivate. [ PJC ]

2. To disband (a military unit, or other group); to discontinue (a group activity); as, to deactivate the regiment; to deactivate the investigation. [ PJC ]

v. t. [ imp. & p. p. inactivated p. pr. & vb. n. inactivating. ] to make inactive; as, boiling will inactivate most enzymes; acetylation of the antibiotic inactivated it.
Syn. -- deactivate. [ WordNet 1.5 +PJC ]

☞ To inactivate an enzyme or chemical usually renders it permanently inactive; to inactivate a machine (as by turning a switch) may be reversible, and for machines and devices, the term deactivate is usually used. The distinction is worth preserving.
[ PJC ]