The Collaborative International Dictionary of English v.0.48:

Acephali \A*ceph"a*li\, n. pl. [LL., pl. of acephalus. See
   Acephal.]
   1. A fabulous people reported by ancient writers to have
      heads.
      [1913 Webster]

   2. (Eccl. Hist.)
      (a) A Christian sect without a leader.
      (b) Bishops and certain clergymen not under regular
          diocesan control.
          [1913 Webster]

   3. A class of levelers in the time of K. Henry I.
      [1913 Webster]