tropism

Etymology

From -tropism (suffix meaning ‘growth towards; movement, turning’) (possibly based on geotropism and heliotropism), from Latin tropus + English -ism (suffix forming nouns of action, process, or result). Tropus is derived from Ancient Greek τρόπος (trópos, “a turn; a manner, style, way; figure of speech, trope; etc.”), from τρέπω (trépō, “to turn; to divert; to rotate or change orientation”) (from Proto-Indo-European *trep- (“to turn”)) + -ος (-os, suffix forming nouns of result or abstract nouns of action). Sense 1 (“turning of an organism or part of an organism towards or away from a stimulus”) is modelled after German Tropismus.