a groove in a shaft, the hub of a wheel, etc., for receiving part of a key
holding it to another part.
a slot in a lock for receiving and guiding the key
(in poured-concrete construction) a longitudinal groove in a footing, or in a pour that has set
, providing a key
for newly poured concrete.
a depression or slot carved into rock to provide a bond or anchorage for a structure, as a dam.