mortise lock 
noun
A lock which is set within the body of a door in a recess or mortise, as opposed to one attached to the door surface.I am replacing an old mortise lock - the skeleton key style one - with a new mortise lock....
- The large sash windows of his 100-year-old home were fitted with bolts, and a mortise lock and a spy hole were fitted in his front door.
- This pattern was created to operate and decorate a mortise lock whose mechanism was built into the fabric of the door.
- County Palatine
- county rate
- county school
- county seat
- county sessions
- county stock
- county town
- county treasurer
- coup
- coup de foudre
- coup de grâce
- coup de main
- coup de maître
- coup de théâtre
- coup d'état
- coup d'œil
- coupe
- couped
- Couperin, François
- coupla
- couple
- coupledom
- coupler
- couples therapist
- couples therapy