/ Dictionary / Index P photochromic: Meaning and Definition of Find definitions for: pho•to•chro•mic Pronunciation: (fō"tu-krō'mik), [key] — adj. (of chemically treated glass or plastic) capable of darkening or changing color when exposed to light. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. photochemistry photochromy Related Content Daily Word Quiz: immense Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language