a helmet is a form of:

Helmet



noun
1.
(protective head covering worn by soldiers, firemen, divers, etc. armor for the head) មួកការពារ
ENGLISH MEANING
noun
1.
A defensive covering for the head.
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.
5.
The upper part of a retort.
6.
The hood-formed upper sepal or petal of some flowers, as of the monkshood or the snapdragon.
7.
A naked shield or protuberance on the top or fore part of the head of a bird.