- the time that the life of someone or something continues; the term of a life: peace within our lifetime.
- 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)
- the length of time that something functions, is useful, etc
- the average time of existence of an unstable or reactive entity, such as a nucleus, excited state, elementary particle, etc; mean life
