65 ILCS 5/10-5-3
For the purposes of this Division 5, "volunteer fireman" or "volunteer member" means a person having regular employment, at work other than that of a fireman, but who is carried on the rolls of a regularly constituted fire department either for the purpose of the prevention or control of fire or the underwater recovery of drowning victims, the members of which are under the jurisdiction of the corporate authorities of city, village or incorporated town and who may receive some compensation for his services as a fireman. "Volunteer fireman" or "volunteer member" does not mean an individual who volunteers assistance and is not a regularly enrolled fireman. However, nothing herein contained shall be construed to prohibit any city, village or incorporated town from procuring insurance to cover persons acting as firemen who are not regularly enrolled as such.
65 ILCS 5/10-5-3