As used in this chapter:
1. The term "joint stock association" includes every unincorporated joint stock association, company or enterprise having written articles of association and capital stock divided into shares, but does not include a corporation or a business trust.2. The term "business trust" means any association operating a business under a written instrument or declaration of trust, the beneficial interest under which is divided into shares represented by certificates.3. The term "stockholder" means every member of a joint stock association.4. The term "association," as used in article four of this chapter, means a joint stock association or a business trust as defined in this section.