-cephalus
combining form in countable noun
denoting a cephalic abnormality
⇒ 
hydrocephalus
Origin
New Latin -cephalus; see -cephalic-ceph·a·lus
noun combining form 
Etymology: New Latin, from Greek -kephalos 
1. plural -cephali : cephalic abnormality (of a specified type) 
< microcephalus >
< hydrocephalus >
2. plural -cepha·li\-ˌlī\  or -cepha·la \-_lə\   : organism having a (specified) type of head 
< Ichthyocephali >
< Phanerocephala >
1. plural -cephali
< microcephalus >
< hydrocephalus >
2. plural -cepha·li
< Ichthyocephali >
< Phanerocephala >