The Collaborative International Dictionary
Photodynamics
Photodynamics \Pho`to*dy*nam"ics\, n. [Photo- + dynamics.] (Plant Physiol.) The relation of light to the movements of plants and their organs; the study of the phenomena of curvatures induced by the stimulus of light. -- Pho`to*dy*nam"ic, Pho`to*dy*nam"ic*al, a.
Wiktionary
photodynamics
n. The study of the activating effects of light on living organisms