/ ˈfɪfti; NAmE /
1.
number 50
2.
noun the fifties [ pl. ] numbers, years or temperatures from 50 to 59 :
She was born in the fifties.
► fif·ti·eth / ˈfɪftiəθ; NAmE / ordinal number , noun
HELP NOTE : There are examples of how to use ordinal numbers at the entry for fifth .
•
IDIOMS
- in your fifties
••
WORD ORIGIN
Old English fīftig (from five and -ty ).