/ Dictionary / Index S SPF: Meaning and Definition of Find definitions for: SPF Pronunciation: [key] sun protection factor: the effectiveness of suntanning preparations in protecting the skin from the harmful effects of the sun's ultraviolet radiation, as rated on a scale of increasing protectiveness from 2 to 15 or sometimes higher. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: spf (Thesaurus) Spezia sp. gr. 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