The Collaborative International Dictionary of English v.0.48:

Miryachit \Mir"ya*chit`\, n. [Written also myriachit.] [Yakoot
   merj[aum]k epileptic, fr. imerek jerk, rage.] (Med.)
   A nervous disease in which the patient involuntarily imitates
   the words or action of another.
   [Webster 1913 Suppl.]