tropismPronunciation: /ˈtrəʊpɪz(ə)m, ˈtrɒp-/Definition of tropism noun [mass noun] Biology the turning of all or part of an organism in a particular direction in response to an external stimulus. Origin: late 19th century: from Greek tropos 'turning' (from trepein 'to turn') + -ismtropism in other Oxford dictionaries Definition of tropism in the US English dictionary
