WordReference Random House Learner's Dictionary of American English © 2026
fif•ty /ˈfɪfti/USA pronunciation
n. [countable], pl. -ties, adj.
adj. [before a noun]
WordReference Random House Unabridged Dictionary of American English © 2026- a cardinal number, ten times five.
- a symbol for this number, as 50 or L.
- fifties, the numbers from 50 through 59, as in referring to the years of a lifetime or of a century or to degrees of temperature:The temperature is in the fifties.
- Informal Termsa fifty-dollar bill.
adj. [before a noun]
- amounting to 50 in number.
fif•ty
(fif′tē),USA pronunciation n., pl. -ties, adj.
n.
adj.
n.
- a cardinal number, ten times five.
- a symbol for this number, as 50 or L.
- a set of this many persons or things.
- fifties, the numbers, years, degrees, or the like, from 50 through 59, as in referring to numbered streets, indicating the years of a lifetime or of a century, or degrees of temperature:She lives in the East Fifties. He's in his late fifties. It's going to be in the fifties again today.
- Informal Termsa fifty-dollar bill:He had a fifty and two tens in his wallet.
adj.
- amounting to 50 in number.
- bef. 900; Middle English; Old English fīftig. See five, -ty1
'in the Fifties' also found in these entries (note: many are not synonyms or translations):