鍵 - key

keyboard (of a piano, typewriter, etc.)

key

cryptographic key; encryption key

latchkey child; latchkey kid

public key encryption

public key cryptosystem

section of road that is curved on purpose as a defensive measure

to have a narrow view of things; to peep at the sky through a keyhole

to lock (a door, etc.); to lock up

keyhole

internal lock

relay key