AcephaliA*ceph"a*li\, n. pl. [LL., pl. of acephalus. See Acephal.]1. A fabulous people reported by ancient writers to have heads. 2. (Eccl. Hist.) (a) A Christian sect without a leader. (b) Bishops and certain clergymen not under regular diocesan control. 3. A class of levelers in the time of K. Henry I.