\Pol"y*chrest\, n. [Gr. ? useful for many purposes;
poly`s many + ? useful, fr. ? to use: cf. F. polychreste.]
(Med.)
A medicine that serves for many uses, or that cures many
diseases. [Obs.]

{Polychrest salt} (Old Med. Chem.), potassium sulphate,
   specifically obtained by fusing niter with sulphur.