Definitions

1. noun

a covering for the head, typically hard, that protects the wearer from injury, especially in sports or military contexts

“The cyclist wore a helmet to prevent head injury in case of a fall.”

2. noun

a protective covering for the head, especially in a particular job or activity

“Firefighters wear helmets to protect their heads from falling objects.”

3. noun

the top or upper part of something

“The helmet of the mushroom was a vibrant red color.”