14 C.F.R. § 375.1
As used in this part:
Air transportation means the carriage by aircraft of persons or property as a common carrier for compensation or hire or the carriage of mail by aircraft in interstate, overseas, or foreign commerce (see 49 U.S.C. 40102(a)(5) and (a)(24) ) ;
Category shall indicate a classification of aircraft such as airplane, helicopter, glider, etc.;
Commercial air operations shall mean operations by foreign civil aircraft engaged in flights for the purpose of crop dusting, pest control, pipeline patrol, mapping, surveying, banner towing, skywriting, or similar agricultural and industrial operations performed in the United States, and any operations for remuneration or hire to, from or within the United States including air carriage involving the discharging or taking on of passengers or cargo at one or more points in the United States, including carriage of cargo for the operator's own account if the cargo is to be resold or otherwise used in the furtherance of a business other than the business of providing carriage by aircraft, but excluding operations pursuant to foreign air carrier permits issued under 49 U.S.C. 41301 , exemptions, and all other operations in air transportation.
Exemption means an exemption granted, under 49 U.S.C. 40109 , authorizing air transportation by a foreign air carrier;
Foreign air carrier permit means a permit authorizing foreign air transportation by a foreign air carrier pursuant to 49 U.S.C. 41301 ;
Foreign aircraft permit means a permit authorizing navigation of foreign civil aircraft in the United States pursuant to 49 U.S.C. 41703 and this part;
Foreign civil aircraft means
Stop for non-traffic purposes means a landing for any purpose other than taking on or discharging passengers, cargo or mail, and does not include landings for embarking or disembarking stopover passengers or transshipped cargo or mail, or for other than strictly operational purposes.
Type means all aircraft of the same basic design including all modifications thereto except those modifications that result in a change in handling or flight characteristics.
14 C.F.R. §375.1