[twen.ty] n, pl twenties [ME, fr. twenty, adj., fr. OE twentig, n., group of 20, fr. twen- (akin to OE twa two) + -tig group of 10; akin to OE tien ten--more at two, ten] (15c) 1: two times ten
2. pl: the numbers 20 to 29; specif: the years 20 to 29 in a lifetime or century
3: a 20-dollar bill -- twen.ti.eth adj or n -- twenty adj -- twenty pron, pl in constr