/ Dictionary / Index S sun protection factor: Meaning and Definition of Find definitions for: sun' protec"tion fac"tor. Pronunciation: [key] See Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. sunproof sunray Related Content Daily Word Quiz: paradox Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language