Mo. Rev. Stat. § 354.464: Names not authorized for use, exceptions.

No health maintenance organization, unless licensed as an insurer, may use in its name, contracts, or literature any of the words "insurance", "casualty", "surety", "mutual", or any other words descriptive of the insurance, casualty, or surety business or deceptively similar to the name or description of any insurance or surety corporation doing business in this state when such words are deceptive or misleading. No person, if not in possession of a valid certificate of authority issued pursuant to sections 354.400 to 354.636, may use the phrase "health maintenance organization" or "HMO" in the course of its operation.