methine
/ˈmɛθʌɪn/ /ˈmiːθʌɪn/ /ˈmɛθiːn/Chemistry
noun
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 Chemical ): designating a dye, pigment, etc., containing one or more such groups.
Origin
Late 19th century; earliest use found in Henry Roscoe (1833–1915), chemist and university administrator. From meth- + -ine.