/ Dictionary / Index E equatorial trough: Meaning and Definition of Find definitions for: e'quato'rial trough' Pronunciation: [key] the quasi-continuous belt of low atmospheric pressure that lies between the subtropical high-pressure belts of the Northern and Southern hemispheres. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. equatorial tide equatorward Related Content Daily Word Quiz: procrastinate Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language