helmet

n. [ OF. helmet, a dim of helme, F. heaume; of Teutonic origin; cf. G. helm, akin to AS. & OS. helm, D. helm, helmet, Icel. hjālmr, 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. çarman protection. √17. Cf. Hele, Hell, Helm a helmet. ] 1. (Armor) A defensive covering for the head. See Casque, Headpiece, Morion, Sallet, and Illust. of Beaver. [ 1913 Webster ]

2. (Her.) The representation of a helmet over shields or coats of arms, denoting gradations of rank by modifications of form. [ 1913 Webster ]

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. [ 1913 Webster ]

4. That which resembles a helmet in form, position, etc.; as: (a) (Chem.) The upper part of a retort. Boyle. (b) (Bot.) The hood-formed upper sepal or petal of some flowers, as of the monkshood or the snapdragon. (c) (Zool.) A naked shield or protuberance on the top or fore part of the head of a bird. [ 1913 Webster ]

Helmet beetle (Zool.), a leaf-eating beetle of the family Chrysomelidae, having a short, broad, and flattened body. Many species are known. --
Helmet shell (Zool.), one of many species of tropical marine univalve shells belonging to Cassis and allied genera. Many of them are large and handsome; several are used for cutting as cameos, and hence are called cameo shells. See King conch. --
Helmet shrike (Zool.), an African wood shrike of the genus Prionodon, having a large crest. [ 1913 Webster ]

a. Wearing a helmet; furnished with or having a helmet or helmet-shaped part; galeate. [ 1913 Webster ]