1) Amino acid 2) Aminoalkanoic acid 3) Amino acid 4) Derivative 
Thyronine is a deiodinated form of thyroxine. ...
HOC6H4-O-C6H4-CH2-CHNH2-COOH;an amino acid with a diphenyl ether group in the side chain; occurs in proteins only in the form of iodinated derivatives (iodothyronines), such as thyroxine. ... (05 Mar 2000) ... 
Type: Term Pronunciation: thī′rō-nēn, -nin Definitions: 1. An amino acid with a diphenyl ether group in the side chain; occurs in proteins only in the form of iodinated derivatives (iodothyronines), such as thyroxine.
[n] - a phenolic amino acid of which thyroxine is a derivative
noun a phenolic amino acid of which thyroxine is a derivative