lifetime

once in a lifetime

only likely to happen once in someone's life. Opportunities to play in the Cup Final only come once in a lifetime so we've got to make the most of it.

See also: once

once-in-a-lifetime

once in a lifetime - only likely to happen once in someone's life. Enter this competition to win a once-in-a-lifetime trip to the Caribbean. (always before noun)

Why break the habit of a lifetime? (British & Australian, humorous)

something that you say which means that you do not believe that someone will stop doing something bad that they have done all their lives. 'I must stop writing my essays the night before the deadline.' 'Why break the habit of a lifetime?'

See also: break, habit, why