35 ILCS 750/1-10
"Debtor" means a taxpayer or other person against whom there is an unpaid final tax liability collectible by the Department.
"Department" means the Department of Revenue.
"Final tax liability" means any State tax, fee, penalty, or interest owed by a person to the Department where the assessment of the liability is not subject to any further timely filed administrative or judicial review.
"Last-known address of the debtor" means the address of the debtor appearing in the records of the Department at the time the notice of tax lien is filed in the registry.
"Person" means any natural individual, firm, partnership, association, joint stock company, joint adventure, public or private corporation, limited liability company, or a receiver, executor, trustee, guardian or other representative appointed by order of any court.
"Registry" or "State Tax Lien Registry" means the public database maintained by the Department wherein tax liens are filed in favor of and enforced by the Department.
35 ILCS 750/1-10