adj. 25B6; adjective
a hilarious story : VERY FUNNY, hysterically funny, hysterical, uproarious, riotous, farcical, rib-tickling; humorous, comic, amusing, entertaining; informal side-splitting, priceless, a scream, a hoot.
a hilarious evening : AMUSING, entertaining, animated, high-spirited, lively, funny, merry, jolly, mirthful, cheerful, uproarious, boisterous; informal wacky.
sad, serious.