头盔由坚硬材料如皮革、金属或塑料制成的头部覆盖物，由橄榄球队员、消防队员、建筑工人、摩托车骑手或其他人配戴，用以保护头部

A head covering of hard material, such as leather, metal, or plastic, worn by football players, firefighters, construction workers, motorcyclists, and others to protect the head.