/ Dictionary / Index R rotary valve: Meaning and Definition of Find definitions for: ro'tary valve' Pronunciation: [key] — Mach. Mach. a valve that rotates continuously or through an arc to open and close. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. rotary tiller rotary wing Related Content Daily Word Quiz: soporific Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language