/ Dictionary / Index P photopathy: Meaning and Definition of Find definitions for: pho•top•a•thy Pronunciation: (fō-top'u-thē), [key] — n. movement of an organism in response to the intensity of light, esp. away from the source of light. any condition or disease produced by the effect of light, esp. in excessive amounts. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. photooxidation photoperiod Related Content Daily Word Quiz: simian Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language