46 C.F.R. § 2.45-1
The following definitions apply to this subpart:
Administration means the Government of the State whose flag the ship is entitled to fly.
Classification society means an organization that, at a minimum, verifies that a vessel meets requirements embodying the technical rules, regulations, standards, guidelines and associated surveys, and inspections covering the design, construction, and/or through life compliance of a ship's structure and essential engineering and electrical systems.
Recognized Organization (RO) means an organization authorized to act on behalf of an Administration.
Regional port state control secretariat means an organization established to collect and maintain port state control inspection data in addition to other functions under a regional agreement among countries.
46 C.F.R. § 2.45-1