- The hole in a lock where the key is inserted and turns.
- (carpentry) A hole or excavation in beams intended to be joined together, to receive the key that fastens them.
- (engineering) A mortise for a key or cotter.
- (lasers) This term needs a definition. Please help out and add a definition, then remove the text
- laser keyhole welding
- keyhole plasma
a hole to lock/unlock with a key