The Collaborative International Dictionary of English v.0.48:

Crocein \Cro"ce*in\ (kr?"s?-?n), n. [See Croceous.] (Chem.)
   A name given to any one of several yellow or scarlet
   dyestuffs of artificial production and complex structure. In
   general they are diazo and sulphonic acid derivatives of
   benzene and naphthol.
   [1913 Webster]