The Collaborative International Dictionary of English v.0.48:

Cyanate \Cy"a*nate\ (s?"?-n?t), n. [Cf. F. cuanate. See
   Cyanic.] (Chem.)
   A salt of cyanic acid.
   [1913 Webster]

   Ammonium cyanate (Chem.), a remarkable white crystalline
      substance, NH4.O.CN, which passes, on standing, to the
      organic compound, urea, CO.(NH2)2.
      [1913 Webster]