/ Dictionary / Index P phototransistor: Meaning and Definition of Find definitions for: pho•to•tran•sis•tor Pronunciation: (fō"tō-tran-zis'tur), [key] — n. Electronics. a transistor that amplifies current induced by photoconductivity. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. phototoxin phototroph Related Content Daily Word Quiz: pristine Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language