once-in-a-lifetime

once-in-a-lifetime (not comparable)

1. Likely to happen only once in one's lifetime; extremely rare.

   Synonym: of a lifetime

   a once-in-a-lifetime opportunity to travel the world

   • 2025 May 11, Nadeen Ebrahim and Abbas Al Lawati, “Trump is visiting three of the world’s richest nations. Here’s what’s on their wish list”, in CNN‎^[1]:

     With Trump in office, they see what one Gulf official called a “once-in-a-lifetime opportunity” to achieve his country’s objectives.