/ Dictionary / Index H hydraulic fluid: Meaning and Definition of Find definitions for: hydrau'lic flu'id Pronunciation: [key] a fluid, usually of low viscosity, as oil, used in a hydraulic system. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. hydraulic coupling hydraulic lift 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