Member. This term means:
(1) An individual, association, partnership, corporation, or trust—
(i) Owning or holding membership in, or admitted to membership representation on, a registered entity; or
(ii) Having trading privileges on a registered entity.
(2) A participant in an alternative trading system that is designated as a contract market pursuant to section 5f of the Act is deemed a member of the contract market for purposes of transactions in security futures products through the contract market.
17 CFR § 1.3
Words used in the singular form in the rules and regulations in this chapter shall be deemed to import the plural and vice versa, as the context may require. The following terms, as used in the Commodity Exchange Act, or in the rules and regulations in this chapter, shall have the meanings hereby assigned to them, unless the context otherwise requires: