ˈtrōˌpizəm noun
( -s )
Etymology: International Scientific Vocabulary -tropism
1.
a. : involuntary orientation by an organism or one of its parts that involves turning or curving accomplished by active movement or more often by structural alteration (as through turgor changes or differential growth), that constitutes a positive or negative response to a source of stimulation (as a light or a temperature or chemical gradient), and that in motile organisms may be indistinguishable from a taxis — compare nastic movement , reflex 4
b. : a reflex reaction involving such movement
2. : an innate tendency to react in a definite manner to stimuli : a natural inborn inclination