"Agency" means each officer, board, commission, and agency created by the Constitution, whether in the executive, legislative, or judicial branch of State government, but other than the circuit court; each officer, department, board, commission, agency, institution, authority, university, and body politic and corporate of the State; each administrative unit or corporate outgrowth of the State government that is created by or pursuant to statute, other than units of local government and their officers, school districts, and boards of election commissioners; and each administrative unit or corporate outgrowth of the above and as may be created by executive order of the Governor. "Agency", however, does not include the following:
5 ILCS 100/1-20