The Collaborative International Dictionary of English v.0.48:

Scelerat \Scel"er*at\, n. [F. sc['e]l['e]rat from L. sceleratus,
   p. p. of scelerare to pollute, from scelus, sceleris, a
   crime.]
   A villain; a criminal. [Obs.] --Cheyne.
   [1913 Webster]