hel ‧ met /ˈhelmət, ˈhelmɪt/ BrE AmE noun [countable]
[ Date: 1400-1500 ; Language: Old French ; Origin: helme 'helmet' ]
a strong hard hat that soldiers, ↑ motorcycle riders, the police etc wear to protect their heads ⇨ ↑ crash helmet , ↑ pith helmet