5 C.F.R. § 591.102

Agency means an “Executive agency,” as defined in 5 U.S.C. 105.

Employee means an employee in or under an agency.

Category of employees means any group of employees designated by an agency that has the same basic uniform requirements.

Head of agency means the head of an agency or an official who has been delegated the authority to act for the head of the agency in the matter concerned.

Uniform means a specified article or articles of clothing or other items that are required by an agency to be worn by an employee to provide a distinctive and easily identifiable appearance in performing his or her job. Examples include hats, shirts, slacks, skirts, neckties, outerwear, name pins or tags, flag pins, rank insignias or cords, or patches. A “uniform” does not include personal protective equipment (PPE) required to be donned for an employee's safety; normal business or work attire (when an employee is not required to wear his or her required uniform); tools, communication devices, or other equipment required in the performance of an employee's job duties; personal items worn at the discretion of the employee (for example, jewelry or undergarments); or any items worn based solely on a reasonable accommodation.

Year means any period of 12 consecutive months designated by an agency as the basis for applying the maximum uniform allowance rates established under this part.