/ Dictionary / Index S sodium pump: Meaning and Definition of Find definitions for: so'dium pump" Pronunciation: [key] an energy-consuming mechanism in cell membranes that transports sodium ions across the membrane, in exchange for potassium ions or other substances. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. sodium propionate sodium pyroborate Related Content Daily Word Quiz: nefarious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language