Plain English Meaning
A pilot who is licensed to be paid to fly. The certificate lets them legally accept money for flying jobs, within the rules that apply to that type of flying.
Full Definition
A pilot who holds an FAA Commercial Pilot Certificate, which authorizes them to act as pilot in command of an aircraft for compensation or hire, subject to the limitations of the certificate and any applicable operating regulations.
Context Anchor
Seen in discussions of pilot certification, practical tests, and the standards a pilot examiner uses when evaluating an applicant for commercial pilot privileges.
Derivation
Commercial comes from the Latin commercium, meaning trade or business. A commercial pilot is one whose flying can be part of a business transaction — flying for pay rather than purely for personal use.