The duration of the life of someone or something. / (informal, hyperbolic) A long period of time.

plural of lifetime

(US) A job in which one remains for one's whole career until one's retirement.

Likely to happen only once in one's lifetime.

plural of lifetime job

(idiomatic) One who achieves great fame while alive.

(dieting) Indulgence in food and drink gives a brief period of sensory pleasure but tends to increase one's body weight in the long term.

A single sexual encounter can lead to a lifetime of disease and treatment.

It is more worthwhile to teach someone to do something (for themselves) than to do it for them (on an ongoing basis).