/ Dictionary / Index P photocatalysis: Meaning and Definition of Find definitions for: pho•to•ca•tal•y•sis Pronunciation: (fō"tō-ku-tal'i-sis), [key] — pl. -ses the acceleration or retardation of the reaction rate in chemical reactions by light. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. photobiotic photocathode Related Content Daily Word Quiz: endear Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language