/ Dictionary / Index H helical gear: Meaning and Definition of Find definitions for: hel'ical gear' Pronunciation: [key] a cylindrical gear wheel whose teeth follow the pitch surface in a helical manner. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. helical helical rack Related Content Daily Word Quiz: belligerent Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language