HILARIOUS definition: 1. extremely funny and causing a lot of laughter: 2. extremely funny and causing a lot of…. Learn more.

Definition of hilarious adjective in Oxford Advanced American Dictionary. Meaning, pronunciation, picture, example sentences, grammar, usage notes, synonyms and more.

1. arousing great merriment; extremely funny. 2. boisterously merry or cheerful: feeling hilarious from the champagne.

Adjective hilarious (comparative more hilarious, superlative most hilarious) Very funny; causing great merriment and laughter. Synonyms: see Thesaurus: funny a hilarious joke Do you like Monty Python? I think they're hilarious. Full of hilarity; merry.

hi lar i ous ly, adv. WordReference Random House Unabridged Dictionary of American English © 2026 hi lar i ous (hi lâr′ ē əs, -lar′ -, hī-), adj. arousing great merriment; extremely funny: a hilarious story; a hilarious old movie. boisterously merry or cheerful: a hilarious celebration. merry; cheerful.

Hilarious means extremely funny, like literally lol funny. Hilarious is most commonly used to describe someone or something (like a joke or a movie) as super funny. Much less commonly, it used to mean very merry or cheerful, as in a hilarious celebration.

If something is hilarious, it is extremely funny and makes you laugh a lot. We thought it was hilarious when we first heard about it. He had a fund of hilarious tales on the subject.

Hilarious is an adjective that describes a high degree of humor. Things that are funny can cause you to smile or giggle, but when something is hilarious, it causes you to laugh out loud.