Mo. Rev. Stat. § 362.421

Any person, association of persons, company or corporation not engaged in the business of banking under the laws of the United States or of the state of Missouri, using the words "bank", "banker", "bankers" or "banking" to designate his or their business or a painted or printed sign at his or their place of business or in a newspaper or any other kind of advertisement or in a letterhead or on an envelope used by him or them, shall be deemed guilty of a misdemeanor and upon conviction fined not less than one hundred dollars.