ˈkask, -aa(ə)-, -ai-, -ȧ- noun
( -s )
Etymology: alteration (influenced by French casque, from Spanish casco ) of cask
1. : a piece of armor for the head : a helmet or military headpiece of any kind
2. : a helmet-shaped hat or headdress
3. : a process or structure suggestive of a helmet: as
a. : the process of the bill of a hornbill
b. : the frontal shield of a coot or gallinule
c. : the covering of bony plates enclosing the head of certain extinct fishes