What does lifetime mean?
A lifetime is the full period during which a person is alive, or more generally the period for which a thing exists, functions, or remains useful. It is often used when discussing long-term commitments, lasting accomplishments, guarantees, and experiences that happen very rarely. The phrase 'once in a lifetime' describes an exceptional event, while 'for a lifetime' can mean either an entire human life or a very long duration. Unlike a simple reference to duration, a lifetime often implies permanence, a complete span of existence, or the limit of a person's opportunities. The word appears in established expressions such as 'lifetime achievement,' 'lifetime guarantee,' and 'a lifetime subscription.' It is a useful term when the focus is not merely on how much time passes, but on the whole arc of a life or the full usable existence of something.
nounThe period during which a person or thing exists, especially the whole span of a person's life. It can also refer to the duration of something's existence or usefulness.
- The entire period of a person's life.
- The period during which something exists, functions, or remains usable.
- An indefinite or very long period of time, especially in the phrase 'for a lifetime'.
"The bridge was built to last for a lifetime."
"She dedicated her lifetime to improving public health."
"The manufacturer offers a lifetime guarantee on the product."
Used when referring to the separate life spans of multiple people or things.
"The biographies compare the lifetimes of several major historical figures."
A lifetime is more than a long stretch of time: it is the whole horizon of a life, and the phrase 'once in a lifetime' captures what can happen only at a rare, unforgettable moment.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does lifetime come from?
The word was formed in Middle English by combining the established elements life and time. Both components are Germanic in origin: life relates to the Old English lif, associated with living, while time comes from Old English tīma. The compound originally conveyed the duration of a person's life and later extended to mean the period of existence or usefulness of any thing.
Related word forms
How lifetime is actually used
The word is common in both formal and informal English. In phrases such as 'a lifetime achievement' and 'a lifetime guarantee,' it may be rhetorical or hyperbolic rather than a literal measurement.
Easily confused with lifetime
A lifespan usually refers specifically to the length of an organism's life, whereas a lifetime can also mean the period during which a person lives or the duration of an object's existence.
Life is the state or fact of being alive, while a lifetime emphasizes the duration of that existence.