The Collaborative International Dictionary of English v.0.48:

Dys- \Dys-\
   An inseparable prefix, fr. the Greek dys- hard, ill, and
   signifying ill, bad, hard, difficult, and the like; cf. the
   prefixes, Skr. dus-, Goth. tuz-, OHG. zur-, G. zer-, AS. to-,
   Icel. tor-, Ir. do-.
   [1913 Webster]