Source : Webster's Revised Unabridged Dictionary (1913)

Serine \Ser"ine\, n. [L. sericus silken.] (Chem.)
   A white crystalline nitrogenous substance obtained by the
   action of dilute sulphuric acid on silk gelatin

Source : WordNet®

serine
     n : a sweetish crystalline amino acid involved in the synthesis
         by the body of cysteine