- the time that the life of someone or something continues; the term of a life: peace within our lifetime.
- Physics. mean life.
- for the duration of a person’s life: He has a lifetime membership in the organization.
- the length of time a person or animal is alive
- (as modifier)a lifetime supply
- 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
n.also life-time, early 13c., from life (n.) + time (n.). One word from 19c. Old English had lifdæg in same sense, literally “life day.” n.
- The period of time during which an individual is alive.
- The period of time during which property, an object, a process, or a phenomenon exists or functions.