内うち鍵かぎ

noun

internal lock; inside key

Refers to a lock or key mechanism on the inside of a door, often a thumb-turn or latch that can be operated from within without a key.

• 内うち鍵かぎをかけてから寝ねてください。

  Please lock the inside lock before you go to bed.

• このドアは内うち鍵かぎが壊こわれているので、外そとからしか開あけられない。

  The inside lock on this door is broken, so it can only be opened from the outside.