As used in this act:

    (a) "Incapacitated individual" means an individual who is impaired by reason of mental illness, mental deficiency, physical illness or disability, chronic use of drugs, chronic intoxication, or other cause, not including minority, to the extent of lacking sufficient understanding or capacity to make or communicate informed decisions.

    (b) "Informal proceedings" means proceedings for probate of a will or appointment of a personal representative conducted by the probate register without notice to interested persons.

    (c) "Interested person" or "person interested in an estate" includes, but is not limited to, the incumbent fiduciary; an heir, devisee, child, spouse, creditor, and beneficiary and any other person that has a property right in or claim against a trust estate or the estate of a decedent, ward, or protected individual; a person that has priority for appointment as personal representative; and a fiduciary representing an interested person. Identification of interested persons may vary from time to time and shall be determined according to the particular purposes of, and matter involved in, a proceeding, and by the supreme court rules.

    (d) "Issue" means an individual's descendant.

    (e) "Joint tenants with the right of survivorship" includes, but is not limited to, co-owners or ownership of property held under circumstances that entitle 1 or more to the whole of the property on the death of the other or others, but does not include forms of co-ownership registration in which the underlying ownership of each party is in proportion to that party's contribution.

    (f) "Jurisdiction," with respect to a geographic area, includes a county, state, or country.

    (g) "Lawyer-guardian ad litem" means an attorney appointed under section 5213 or 5219 who has the powers and duties referenced by and provided in section 5213.

    (h) "Lease" includes, but is not limited to, an oil, gas, or other mineral lease.

    (i) "Legally incapacitated individual" means an individual, other than a minor, for whom a guardian is appointed under this act or an individual, other than a minor, who has been adjudged by a court to be an incapacitated individual.

    (j) "Letters" includes, but is not limited to, letters testamentary, letters of guardianship, letters of administration, and letters of conservatorship.