a·ceph·a·lous 
(ā-sĕfə-ləs)
(ā-sĕfə-ləs)adj.
1. Biology Headless or lacking a clearly defined head: acephalous worms.
2. Having no leader.
[From Medieval Latin acephalus, from Greek akephalos : a-, without; see A-1 + kephalē, head; see -CEPHALOUS.]