/ Dictionary / Index E essential amino acid: Meaning and Definition of Find definitions for: essen'tial ami'no ac'id Pronunciation: [key] — Biochem. Biochem. any amino acid that is required by an animal for growth but that cannot be synthesized by the animal's cells and must be supplied in the diet. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. essential essential hypertension Related Content Daily Word Quiz: fabricate Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language