helmet

helmet is a   Noun

Definition:

[1] A defensive covering for the head. See Casque, Headpiece, Morion, Sallet, and Illust. of Beaver.

[2] The representation of a helmet over shields or coats of arms, denoting gradations of rank by modifications of form.

[3] A helmet-shaped hat, made of cork, felt, metal, or other suitable material, worn as part of the uniform of soldiers, firemen, etc., also worn in hot countries as a protection from the heat of the sun.

[4] That which resembles a helmet in form, position, etc.; as:

Synonyms: