合あい鍵かぎ

noun

duplicate key; copy of a key

A key made as a copy of an original, often without the owner's knowledge.

• 彼かの女じょはこっそり合あい鍵かぎを作つくった。

  She secretly made a duplicate key.

noun

master key; passkey; skeleton key

A key that can open multiple locks; less common than the duplicate key sense.

• 管かん理り人にんは合あい鍵かぎで全すべての部屋へやに入はいれる。

  The caretaker can enter all rooms with a master key.