once in a lifetime

once in a lifetime

Describing something, such as an opportunity, experience, or situation, that seems unlikely to happen again. Often hyphenated when used as a modifier before a noun. You have to take this job in the Zurich office—it's a once-in-a-lifetime opportunity to live in Switzerland. Chances like this only ever come around once in a lifetime, Jack, so don't waste it.
See also: lifetime, once
Farlex Dictionary of Idioms.

once in a lifetime

Extremely rare, especially as an opportunity. For example, An offer like that will come just once in a lifetime. This phrase, often used hyperbolically, was first recorded in 1854. Also see of one's life.
See also: lifetime, once
The American Heritage® Dictionary of Idioms by Christine Ammer.
See also:
  • every woman for herself
  • eleventh hour
  • a light touch
  • out of context
  • first hand
  • carrot
  • carrot and stick
  • carrot-and-stick
  • a round robin
  • round robin
References in periodicals archive
Don't miss this once in a lifetime event, as the Philippines last observed a super blue blood moon occurence on Dec.
Where to spot the super blue blood moon in PH
This threat, which Allen had no right to appeal, became a publicity death sentence when Mauch told reporters, "I had to choose between a thirty-six-year-old veteran who was hitting .250 and a twenty-three-year-old power hitter who was hitting .348, the kind of player you see once in a lifetime." Mauch, who had a testy relationship with his black players, had already been irritated by his star's increasingly prima donna-like behavior, while Allen mistakenly thought the controversy would blow over.
Locker-room liberty: athletes who helped shape our times and the economic freedom that enabled them