from The American Heritage® Dictionary of the English Language, 4th Edition
- n. An essential amino acid, C9H11NO2, that occurs as a constituent of many proteins and is normally converted to tyrosine in the human body. It is necessary for growth in infants and for nitrogen equilibrium in adults.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. An essential amino acid C9H11NO2 found in most animal proteins; it is essential for growth; the inability to metabolize it leads to phenylketonuria; it is a constituent of aspartame.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. an essential amino acid found in proteins and needed for growth of children and for protein metabolism in children and adults; abundant in milk and eggs; it is normally converted to tyrosine in the human body
From phenyl and alanine. (Wiktionary)