n. & adj.
n. (pl. -ies) 1 the product of four and ten. 2 a symbol for this (40, xl, XL). 3 (in pl.) the numbers from 40 to 49, esp. the years of a century or of a person's life. 4 (the Forties) Brit. the sea area between the NE coast of Scotland and the SW coast of Norway (so called from its depth of forty fathoms or more).
adj. that amount to forty. forty-first, -second , etc. the ordinal numbers between fortieth and fiftieth. forty-five a gramophone record played at 45 r.p.m. the Forty-five the Jacobite rebellion of 1745. forty-niner US a seeker for gold etc., esp. in the Californian gold-rush of 1849. forty-one, -two , etc. the cardinal numbers between forty and fifty. forty winks colloq. a short sleep. fortieth adj. & n. fortyfold adj. & adv.
[ OE feowertig (as FOUR, -TY(2)) ]