Source : Webster's Revised Unabridged Dictionary (1913)

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