GRUNION Meaning of GRUNION in English [ 'grʌnjən ]■ noun a small, slender Californian fish that swarms on to beaches to spawn. [ Leuresthes tenuis .]Originearly 20th cent.: prob. from Sp. gruñón 'grunter'. Concise Oxford English vocab. Сжатый оксфордский словарь английского языка. 2004