/ Dictionary / Index S synchronous speed: Meaning and Definition of Find definitions for: syn'chronous speed' Pronunciation: [key] — Elect. Elect. the speed at which an alternating-current machine must operate to generate electromotive force at a given frequency. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. synchronous rotation synchrony Related Content Daily Word Quiz: resilient Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language