adjective
- not active: an inactive volcano.
- sedentary or passive: an inactive life.
- sluggish; indolent.
- Military. not on active duty.
- Chemistry.
- inert; unreactive.
- noting a compound that has no effect on polarized light.
adjective
- idle or inert; not active
- sluggish, passive, or indolent
- military of or relating to persons or equipment not in active service
- chem (of a substance) having little or no reactivity
- (of an element, isotope, etc) having little or no radioactivity
1640s, from in- (1) “not, opposite of” + activity. Phrase masterly inactivity attested by 1791.