D defs.my
Entry 2 senses Webster, 1913

Keyhole

/kēh'-ōlˌ/ · Key·hole · IPA /ˈkiˌhoʊl/
01 n. A hole or apertupe in a door or lock, for receiving a key.
  1. 1.
    A hole or apertupe in a door or lock, for receiving a key.
  2. 2.
    A hole or excavation in beams intended to be joined together, to receive the key which fastens them.(Carp.)
Phrases & compounds
Keyhole limpet — a marine gastropod of the genus Fissurella and allied genera. See Fissurella.
Keyhole saw — a narrow, slender saw, used in cutting keyholes, etc., as in doors; a kind of compass saw or fret saw.
Keyhole urchin — any one of numerous clypeastroid sea urchins, of the genera Melitta, Rotula, and Encope; -- so called because they have one or more perforations resembling keyholes.