from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. One of the naturally occurring amino acids that the human body cannot synthesize, and so must be provided by dietary protein.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. an amino acid that is required by animals but that they cannot synthesize; must be supplied in the diet
See essential and amino acid. (Wiktionary)