The Collaborative International Dictionary of English v.0.48:

Idiocrasy \Id`i*oc"ra*sy\, n.; pl. Idiocrasies. [Idio- + Gr.
   kra^sis a mixture, fr. ? to mix: cf. F. idiocrasie.]
   Peculiarity of constitution; that temperament, or state of
   constitution, which is peculiar to a person; idiosyncrasy.
   Idiocratic