'Phototropism' definitions:

Definition of 'phototropism'

From: WordNet
noun
An orienting response to light

Definition of 'Phototropism'

From: GCIDE
  • Phototropism \Pho*tot"ro*pism\, n. [Photo- + Gr. ? to turn.]
  • 1. (Plant Physiol.) The tendency of growing plant organs to move or curve under the influence of light. In ordinary use the term is practically synonymous with heliotropism. [Webster 1913 Suppl.]
  • 2. (Microbiology) exhibiting movement in a direction toward (positive phototropism) or away from ({negative phototropism}) a source of light. [PJC]