/ Dictionary / Index P photoelectric threshold: Meaning and Definition of Find definitions for: pho'toelec'tric thresh'old Pronunciation: [key] — Physics. Physics. the minimum frequency or maximum wavelength of incident radiation necessary to release photons from a given surface. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. photoelectric meter photoelectric tube Related Content Daily Word Quiz: belligerent Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language