noun, plural fif·ties.
- 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. a fifty-dollar bill: He had a fifty and two tens in his wallet.
- amounting to 50 in number.
noun plural -ties
- the cardinal number that is the product of ten and five
- a numeral, 50, L, etc, representing this number
- something represented by, representing, or consisting of 50 units
- amounting to fiftyfifty people
- (as pronoun)fifty should be sufficient
1826 as the years of someone’s life between 50 and 59; 1853 as a decade of years in a given century. See fifty.
Old English fiftig, from fif “five” (see five) + -tig “group of ten” (see -ty (1)). Cf. Old Frisian fiftich, Old Norse fimm tigir, Dutch vijftig, Old High German fimfzug, German fünfzig, Gothic fimf tigjus. U.S. colloquial fifty-fifty “in an even division” is from 1913.