名词

1. 一生；终生
A lifetime is the length of time that someone is alive.

2. （事物的）存在期，使用期
The lifetime of a particular thing is the period of time that it lasts.

3. 终生难遇的；千载难逢的
If you describe something as the chance or experience of a lifetime, you are emphasizing that it is the best or most important chance or experience that you are ever likely to have.

1. the period during which something is functional (as between birth and death)

e.g. the battery had a short life
he lived a long and happy life

Synonym: lifelife-timelifespan