keyway

noun5

1. •
   A slot into which a precision attachment (a key) is fitted.
2. •
   The recessed part of a keyed joint, in which the key resides.
3. •
   The whole deep way the key has to go, the hollow or cavity.
4. •
   The groove within a modern lock that the key slides into; any lock's keyhole.
5. •
   A guide groove.