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.
(Science: chemistry) As: The upper part of a retort.
(Science: botany) a naked shield or protuberance on the top or fore part of the head of a bird. Helmet beetle, an african wood shrike of the genus Prionodon, having a large crest.
Origin: OF. Helmet, a dim of helme, f. Heaume; of teutonic origin; cf. G. Helm, akin to as. & os. Helm, D. Helm, helmet, Icel. Hjalmr, Sw. Hjelm, dan. Hielm, goth. Hilms; and prob. From the root of as. Helan to hide, to hele; cf. Also lith. Szalmas, Russ. Shleme, Skr. Carman protection. Cf. Hele, hell, Helm a helmet.