the time that the life of someone or something continues; the term of a life:
peace within our lifetime.
for the duration of a person’s life:
He has a lifetime membership in the organization.
the length of time that something functions, is useful, etc
(physics) the average time of existence of an unstable or reactive entity, such as a nucleus, excited state, elementary particle, etc; mean life
also life-time, early 13c., from life (n.) + time (n.). One word from 19c. Old English had lifdæg in same sense, literally “life day.”
lifetime life·time (līf’tīm’)
noun 1. .
[lahyf-wey] /ˈlaɪfˌweɪ/ noun 1. a way of life; a manner of living. 2. any of the customs and practices of a culture. n. “way of life,” 1960s, an unconscious revival of Old English lifweg; see life (n.) + way.
[lahyf-wurk] /ˈlaɪfˈwɜrk/ noun 1. the complete or principal , labor, or task of a lifetime.
noun 1. a geographic region characterized by a distinct set of animals and plants.