49 C.F.R. § 1510.3
In addition to the definitions in §§ 1500.3 , 1503.103 , and 1540.5 of this chapter, the following terms are used in this part:
Air carrier means a citizen of the United States who undertakes directly to engage in or provide air transportation.
Air transportation means continental interstate air transportation, continental intrastate air transportation, foreign air transportation, non-continental interstate air transportation, or non-continental intrastate air transportation.
Aircraft means a device that is used or intended to be used for flight in the air.
Airport means any landing area used regularly by aircraft for receiving or discharging passengers or cargo.
Continental interstate air transportation means the carriage by aircraft of persons for compensation or hire within the continental United States.
Continental intrastate air transportation means the carriage by aircraft of persons for compensation or hire wholly within the same state of the continental United States.
Continental United States means the District of Columbia and the States other than Alaska and Hawaii.
Co-terminal means an airport serving a multi-airport city or metropolitan area that has been approved by TSA to be used as the same point for purposes of determining application of the security service fee imposed under § 1510.5 of this part. Copies of the approved list are available on TSA's Web site at www.tsa.gov or by contacting tsa-fees@dhs.gov.
Direct air carrier and foreign air carrier means a selling carrier.
Foreign air carrier means any person other than a citizen of the United States who undertakes directly to engage in or provide air transportation.
Foreign air transportation means the carriage by aircraft of persons for compensation or hire between a place in the United States and any place outside of the United States.
Frequent flyer award means a zero-fare award of air transportation that a domestic air carrier or foreign air carrier provides to a passenger in exchange for accumulated travel mileage credits in a customer loyalty program, whether or not the term frequent flyer is used in the definition of that program.
Non-continental interstate air transportation means the carriage by aircraft of persons for compensation or hire within the United States, but outside the continental United States.
Non-continental intrastate air transportation means the carriage by aircraft of persons for compensation or hire wholly within the same state, territory or possession of the United States, but outside the continental United States.
Nonrevenue passenger means a passenger receiving air transportation from an air carrier or foreign air carrier for which the air carrier or foreign air carrier does not receive remuneration.
One-way trip means continuous air transportation, during which a stopover does not occur; there may be multiple one-way trips on the same air travel itinerary.
Origin point means the location at which a trip on a complete air travel itinerary begins.
Principal means the aggregate amount of all passenger security services fees due to be remitted to the Transportation Security Administration by an air carrier as required by this part.
Round trip means a trip on an air travel itinerary that terminates or has a stopover at the origin point (or co-terminal).
Selling carrier means an air carrier or foreign air carrier that provides or offers to provide air transportation and has control over the operational functions performed in providing that air transportation.
Stopover means a break in travel of more than:
Terminates means the location at which a trip on a complete air travel itinerary ends.
49 C.F.R. §1510.3