hy·drot·ro·pism (hī-drŏt'rə-pĭz'əm) n. Growth or movement in a sessile organism toward or away from water, as of the roots of a plant. hy'dro·tro'pic (hī'drə-trō'pĭk, -trŏp'ĭk) adj., hy'dro·tro'pi·cal·ly adv.
Main Entry: hy·dro·tro·pism Pronunciation: hI-'drä-tr&-"piz-&m; "hI-dr&-'trO-"piz-&m, -'trä- Function: noun : a tropism in which water or water vapor is the orienting factor