Source : Webster's Revised Unabridged Dictionary (1913)

Athetosis \Ath`e*to"sis\, n. [NL., fr. Gr. ? not fixed; 'a priv.
   + ? to set.] (Med.)
   A variety of chorea, marked by peculiar tremors of the
   fingers and toes.

Source : WordNet®

athetosis
     n : a continuous succession of slow writing involuntary
         movements of the hands and feet and other body parts