noun.
One who contracts; one of the parties to a contract, bargain, or agreement; one who covenants with another to do or to refrain from doing a particular thing.
noun.
Specifically One who contracts or covenants, either with a government or other public body or with private parties, to furnish supplies, or to construct works or erect buildings, or to perform any work or service, at a certain price or rate: as, a paving-contractor; a labor-contractor.
noun.
A muscle which contracts or lessens the size of a part; a constrictor.