[eighty] n, pl eight.ies [ME eighty, adj., fr. OE eahtatig, short for hundeahtatig, n., group of eighty, fr. hund-, lit., hundred + eahta eight + -tig group of ten; akin to OE tien ten] (bef. 12c) 1: eight times ten
2. pl: the numbers 80 to 89; specif: the years 80 to 89 in a lifetime or century -- eight.i.eth adj or n -- eighty adj -- eighty pron, pl in constr