From Longman Dictionary of Contemporary Englishkeyholekey‧hole /ˈkiːhəʊl $ -hoʊl/ noun [countable] DHthe hole in a lock that you put the key in I peeped through the keyhole and watched them.
Examples from the Corpus
keyhole• An example would be a keyhole shaped in such a way that one can physically insert the key only right side up.• I could see daylight through a keyhole.• And there was no keyhole, and thus no lock to pick.• Loyd Grossman went through Gary's keyhole and didn't come back for three months.• I heard the scraping of a key in the keyhole.• To hell with you, Nevil Sanderson! she thought as she inserted her key into the keyhole.• Basingstoke and North Hampshire Medical Trust have hosted a special reception evening launching phase two of the keyhole surgery appeal.• We do have a few glimpses, through the keyhole as it were. 