鍵
a small piece of shaped metal with incisions cut to fit the wards of a particular lock, which is inserted into a lock and turned to open or close it.
:
• I can't find my car keys.
車の鍵が見つからない。
• She locked the door and put the key in her pocket.
彼女はドアに鍵をかけ、鍵をポケットに入れた。