Complainant
Black's Law Dictionary · Henry Campbell Black, M.A. · 1910
Black's Law Dictionary
In practice
One who applies to the courts for legal redress; one who exhibits a bill of complaint This is the proper designation of one suing in equity, though "plaintiff" is often used in equity proceedings as well as at law.
Benefit Ass'n v. Robinson, 147 I1L 138, 35 N. E. 168.