Hel·met n.
 1. Armor A defensive covering for the head. See Casque, Headpiece, Morion, Sallet, and Illust. of Beaver.
 2. Her. 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: (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.
 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.
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