1827 as the years of someone's life between ages 80 and 89; from 1833 as the ninth decade of years in a given century; from 1854 with reference to Fahrenheit temperature. See eighty.
Entries linking to eighties
eighty adj., n.
"1 more than seventy-nine, twice forty; the number which is one more than seventy-nine; a symbol representing this number;" late 13c., eigteti, from eight + -ty (1). Replacing Old English hundeahtatig, with hund- "ten." Related: Eightieth.