(a) As used in Article 4:

(i) 'Any interest in property' includes, but is not limited to an undivided portion of an interest and a power with respect to property;

(ii) 'Disclaimer' means an irrevocable and unqualified refusal by a person to accept an interest in property;

(iii) 'Fiduciary' means a personal representative, trustee, agent acting under a power of attorney or other person authorized to act as a fiduciary with respect to the property of another person.