625 ILCS 5/1-182

(a) "School bus" means every motor vehicle, except as provided in paragraph (b) of this Section, owned or operated by or for any of the following entities for the transportation of persons regularly enrolled as students in grade 12 or below in connection with any activity of such entity: Any public or private primary or secondary school; Any primary or secondary school operated by a religious institution; or Any public, private or religious nursery school. (b) This definition shall not include the following: 1. A bus operated by a public utility, municipal corporation or common carrier authorized to conduct local or interurban transportation of passengers when such bus is not traveling a specific school bus route but is: On a regularly scheduled route for the transportation of other fare paying passengers; Furnishing charter service for the transportation of groups on field trips or other special trips or in connection with other special events; or Being used for shuttle service between attendance centers or other educational facilities. 2. A motor vehicle of the First Division. 3. A multifunction school-activity bus.