/ Dictionary / Index S smooth sumac: Meaning and Definition of Find definitions for: smooth' su'mac Pronunciation: [key] a shrub or small tree, Rhus glabra, of the cashew family, native to North America, having pinnate leaves and green flowers in a dense terminal cluster. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. smooth-spoken smooth-talk 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