n.
Pronunciation: ˌ h ō -m ō - ' sis-t ə - ˌ ē n, ˌ hä-
Function: noun
Etymology: International Scientific Vocabulary hom- + cysteine
Date: 1932
: an amino acid C 4 H 9 NO 2 S that is produced in animal metabolism by the demethylation of methionine and that appears to be associated with an increased risk of cardiovascular disease when occurring at high levels in the blood