Contractor includes a subcontractor whose subcontract is subject to provisions of the Act. Also, the termemployermeans, and is used interchangeably with, the termscontractorandsubcontractorin various sections in this part. The U.S. Government, its agencies, and instrumentalities are not contractors, subcontractors, employers or joint employers for purposes of compliance with the provisions of the Act.
29 CFR § 4.1a
As used in this part, unless otherwise indicated by the context -