nanocephaly vs microcephalus

nanocephaly and microcephalus both are nouns.

Word	Noun	Adjective	Verb	Adverb
nanocephaly	Yes	No	No	No
microcephalus	Yes	No	No	No

As nouns, nanocephaly and microcephalus are synonyms defined as:

nanocephaly and microcephalus: an abnormally small head and underdeveloped brain

Other synonyms of nanocephaly include microcephaly.

nanocephaly (noun)	microcephalus (noun)
an abnormally small head and underdeveloped brain	an abnormally small head and underdeveloped brain