A trivalent group or radical consisting of a carbon and a hydrogen atom, specifically the group =CH—; also called methene or methenyl. Also (especially in Dye Chemistry): designating a dye, pigment, etc., containing one or more such groups.
methine/ˈmɛθʌɪn/ /ˈmiːθʌɪn/ /ˈmɛθiːn/
Late 19th century; earliest use found in Henry Roscoe (1833–1915), chemist and university administrator. From meth- + -ine.