cap (hat); baseball cap
Refers to a brimmed hat, especially a baseball-style cap. Not used for formal hats or winter beanies.
He put on his baseball cap and went outside.
He always wears a red cap.
cap (of a bottle, pen, etc.); lid
Used for small removable covers, such as bottle caps, pen caps, or lens caps. For larger lids or pot covers, ふた is more common.
I lost the cap of my pen.
Please close the bottle cap tightly.
I took the cap off the pen and started writing.
Please close the bottle cap right after using it.
キャップ is the common loanword for a cap or cover on things like pens and bottles, while 鞘 is the more traditional term especially for writing instruments.
nightcap
bubble wrap; air-cap packaging · tire valve cap · Air Cap (lawn mower brand)
capless; without a cap
cap seal
cap height
cap light
capline
cap lamp; headlamp (for a hard hat)
cap rock
dunce cap; fool's cap
Borrowed from English 'cap'.
nurse's cap