tight-fitting cap
nounUK /ˌtaɪt ˈfɪtɪŋ kæp/
US /ˌtaɪt ˈfɪtɪŋ kæp/
A cap that fits very closely to your head.
The swimmer wore a tight-fitting cap to keep her hair dry.
OTHER MEANINGS
2. A small lid or cover that seals tightly on a container.
He screwed the tight-fitting cap back onto the bottle.
3. A protective cover that grips closely around a machine part or pipe.
The mechanic replaced the tight-fitting cap on the valve.
4. A close-fitting hat worn as part of a uniform.
The nurse's tight-fitting cap stayed in place all day.