Hilarious Definition

hĭ-lârē-əs, -lăr-, hī-
adjective
Noisily merry; boisterous and joyous.
Webster's New World
Characterized by or causing great merriment.
American Heritage
Producing much laughter; very funny.
Webster's New World

Origin of Hilarious

  • From Latin hilaris (“cheerful”), from Ancient Greek ἱλαρός (hilaros, “cheerful, merry”), from ἵλαος (hilaos, “propitious, gracious, kind”).

    From Wiktionary

  • Latin hilaris cheerful hilarity –ious

    From American Heritage Dictionary of the English Language, 5th Edition