Affixes

Adjectives in ‑cephalic and ‑cephalous are usually equivalent in meaning, though the former is more common. Examples are hydrocephalic (literally, having water on the head) in reference to a child suffering from an enlarged head because of fluid retention; brachycephalic (Greek brakhus, short), having a relatively broad, short skull; microcephalic (Greek mikros, small), abnormal smallness of the head, a congenital condition associated with incomplete brain development; bicephalous (Latin bi, having two), having two heads.

Nouns in ‑cephalus or ‑cephaly refer to the condition: hydrocephalus; microcephaly; macrocephalus; plagiocephaly (Greek plagios, slanting), oblique deformity of the head. With the exception of hydrocephalus, forms in ‑cephalus are generally less common than those in ‑cephaly.