Definition of once in a lifetime
- a once-in-a-lifetime opportunity
- This sort of opportunity comes along once in a lifetime.
: one time and no more
: at any one time : under any circumstances : ever
: at some indefinite time in the past : formerly
: one single time : one time at least
: that once was : former
: at the moment when : as soon as
: the duration of the existence of a living being (such as a person or an animal) or a thing (such as a star or a subatomic particle)
: an amount accumulated or experienced in a lifetime
: of long duration or continuance
: measured or achieved over the span of a career
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