- the period of time that someone lives, or that something lasts, functions, or is in effect
- a very long time: made to last a lifetime
- 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.
- Continuing for a lifetime; lifelong.
- Occurring or measured over a person's active career: a lifetime batting average.
- The duration of the life of someone or something.
- (informal, hyperbolic) A long period of time.
- I've been waiting a lifetime for a train.