Akademik

a padded helmet worn by people riding bicycles or motorcycles; protects the head in case of accidents

noun, pl ⋯ -mets [count]

: a very strong, hard hat that is worn to protect your head when you are riding a bicycle, motorcycle, etc.

ˈcrash helmet [crash helmet crash helmets] noun

a hat made of very strong material and worn when riding a motorcycle to protect the head