735 ILCS 5/2-401: Designation of parties - Misnomer.

(a) The party commencing an action shall be called the plaintiff. The adverse party shall be called the defendant.

(b) Misnomer of a party is not a ground for dismissal but the name of any party may be corrected at any time, before or after judgment, on motion, upon any terms and proof that the court requires.

(c) A party shall set forth in the body of his or her pleading the names of all parties for and against whom relief is sought thereby.

(d) Unless a contrary meaning is indicated, wherever used in this Act and in rules adopted pursuant hereto the term "plaintiff" includes counterclaimants and third-party plaintiffs, and the term "defendant" includes third-party defendants and parties against whom relief is sought by counterclaim.

(e) Upon application and for good cause shown the parties may appear under fictitious names.