\Hy*drot"ro*pism\, n. (Bot.)
A tendency towards moisture.

\Hy*drot"ro*pism\, n. (Bot.)
In a broader sense, any curvature or turning induced in
certain growing plant organs under the influence of moisture.
Note: When the movement is toward the moisture, as is the
      case in most roots, the phenomenon is called {positive
      hydrotropism}; when away from the moisture, as in the
      case of hyphae of certain fungi, {negative
      hydrotropism}.