The Collaborative International Dictionary of English v.0.48:

Rusma \Rus"ma\, n. [Corrupt. from Turk. khyryzma a paste used as
   a depilatory, fr. Gr. ? an unguent; cf. F. rusma.]
   A depilatory made of orpiment and quicklime, and used by the
   Turks. See Rhusma.
   [1913 Webster]