Complaint
late Middle English: from Old French complainte, feminine past participle of complaindre ‘to lament’ (see complain).
wiktionary
From Middle English compleynte, from Anglo-Norman compleint, from Old French compleindre, eventually from Latin planctus (whence plaint).
etymonline
complaint (n.)
late 14c., "lamentation, expression of grief," also "grief, sorrow, anguish" itself; also "expression of dissatisfaction or disapproval; statement of grievances, formal accusation; a plaintive poem," from Old French complainte (12c.) "complaint, lament," noun use of fem. past participle of complaindre "to lament" (see complain). Meaning "that which is complained of" is from 1745; specific meaning "bodily ailment, cause of pain or uneasiness" is from 1705 (often in U.S. colloquial use generalized as complaints).
