-ˌsēn, -_sə̇n noun
( -s )
Etymology: irregular from Greek tyros cheese + International Scientific Vocabulary -ine — more at butter
1. : a crystalline phenolic alpha-amino acid HOC 6 H 4 CH 2 CH(NH 2 )COOH obtained in its levorotatory l form by the hydrolysis of proteins (as casein or fibroin) and also made synthetically in the racemic form; para -hydroxy-phenylalanine
2. : either of two crystalline acids that are ortho and meta isomers of tyrosine — compare diiodotyrosine , dopa , thyronine