n. & adj.
n. (pl. -ies) 1 the product of three and ten. 2 a symbol for this (30, xxx, XXX). 3 (in pl.) the numbers from 30 to 39, esp. the years of a century or of a person's life.
adj. that amount to thirty. thirty-first, -second , etc. the ordinal numbers between thirtieth and fortieth. Thirty-nine Articles the points of doctrine assented to by those taking orders in the Church of England. thirty-one, -two , etc. the cardinal numbers between thirty and forty. thirty-second note esp. US Mus. = DEMISEMIQUAVER. thirty-two-mo a book with 32 leaves to the printing-sheet. thirtieth adj. & n. thirtyfold adj. & adv.
[ OE thritig (as THREE, -TY(2)) ]