14 CFR §21.1

1. (a)This part prescribes—
   1. (1)Procedural requirements for issuing and changing—
      1. (i)Design approvals;
      2. (ii)Production approvals;
      3. (iii)Airworthiness certificates; and
      4. (iv)Airworthiness approvals;
   2. (2)Rules governing applicants for, and holders of, any approval or certificate specified in paragraph (a)(1) of this section; and
   3. (3)Procedural requirements for the approval of articles.
2. (b)For the purposes of this part—
   1. (1)Airworthiness approval means a document, issued by the FAA for an aircraft, aircraft engine, propeller, or article, which certifies that the aircraft, aircraft engine, propeller, or article conforms to its approved design and is in a condition for safe operation, unless otherwise specified;
   2. (2)Article means a material, part, component, process, or appliance;
   3. (3)Commercial part means an article that is listed on an FAA-approved Commercial Parts List included in a design approval holder's Instructions for Continued Airworthiness required by § 21.50;
   4. (4)Design approval means a type certificate (including amended and supplemental type certificates) or the approved design under a PMA, TSO authorization, letter of TSO design approval, or other approved design;
   5. (5)Interface component means an article that serves as a functional interface between an aircraft and an aircraft engine, an aircraft engine and a propeller, or an aircraft and a propeller. An interface component is designated by the holder of the type certificate or the supplemental type certificate who controls the approved design data for that article;
   6. (6)Product means an aircraft, aircraft engine, or propeller;
   7. (7)Production approval means a document issued by the FAA to a person that allows the production of a product or article in accordance with its approved design and approved quality system, and can take the form of a production certificate, a PMA, or a TSO authorization;
   8. (8)State of Design means the country or jurisdiction having regulatory authority over the organization responsible for the design and continued airworthiness of a civil aeronautical product or article;
   9. (9)State of Manufacture means the country or jurisdiction having regulatory authority over the organization responsible for the production and airworthiness of a civil aeronautical product or article.
   10. (10)Supplier means a person at any tier in the supply chain who provides a product, article, or service that is used or consumed in the design or manufacture of, or installed on, a product or article.