acrania
noun
acra·nia
| \ (ˈ)ā-ˈkrā-nē-ə
\
\
Medical Definition of acrania
(Entry 1 of 2)
: congenital partial or total absence of the skull
Acrania
noun pluralMedical Definition of Acrania (Entry 2 of 2)
in some classifications
: a division of the phylum or subkingdom Chordata comprising the hemichordates, tunicates, and lancelets and including all the chordates without true heads and anterior brains — compare vertebrata