Pronunciation: (kā'sēn, -sē-in, kā-sēn'),[key] —n. 1. Biochem.a protein precipitated from milk, as by rennet, and forming the basis of cheese and certain plastics.
2. Fine Arts. a. an emulsion made from a solution of this precipitated protein, water, and ammonia carbonate.
b. a paint in which this emulsion is used as a binder.
c. a picture produced with this paint and emulsion.