Breadcrumb Home > Dictionary > Index S single-acting: Meaning and Definition of Find definitions for: sin•gle-act•ing Pronunciation: (sing'gul-ak'ting), [key] — adj. (of a reciprocating engine, pump, etc.) having pistons accomplishing work only in one direction. Cf.(def. 1). Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. single single-action ✖ Related Content Daily Word Quiz: umbrage Analogy of the Day: Today’s Analogy Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language