/ Dictionary / Index S S.L.P.: Meaning and Definition of Find definitions for: S.L.P. Pronunciation: [key] Socialist Labor Party. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. sloyd SLR Related Content Daily Word Quiz: procrastinate Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language