HILARIOUS Meaning of HILARIOUS in English [ hɪ'lɛ:rɪəs ]■ adjective extremely amusing.Derivatives~ly adverb OriginC19 (earlier (ME) as hilarity ): from L. hilaris (from Gk hilaros 'cheerful') + -ous . Concise Oxford English vocab. Сжатый оксфордский словарь английского языка. 2004