com·plain / kəmˈplān/ • v. [tr.] express dissatisfaction or annoyance about a state of affairs or an event: local authorities complained that they lacked sufficient resources [intr.] we all complained about the food. ∎  [intr.] (complain of) state that one is suffering from (a pain or other symptom of illness): complaining of headaches. ∎  [intr.] state a grievance: they complained to the French government. ∎  [intr.] poetic/lit. make a mournful sound. ∎  [intr.] (of a structure or mechanism) groan or creak under strain.DERIVATIVES: com·plain·er n.com·plain·ing·ly adv.

complain XIV. ME. compleigne — (O)F. complaign-, pres. stem of complaindre (orig. refl.) :- Rom. (medL.) complangere, f. COM- (intensive) + plangere lament (cf. PLAINT).
So complaint XIV.