The term "business trust" whenever used or referred to in this Article shall mean any unincorporated association, including an Illinois land trust, a Delaware statutory trust, or a Massachusetts business trust, engaged in any business or trade under a written instrument or declaration of trust under which the beneficial interest therein is divided into shares represented by certificates or shares of beneficial interest. (1977, c. 768, s. 1; 2009-174, s. 1.)