Other forms: complained, complaining, complains
To complain is to say you are unhappy about something, out loud and more than once. The food was cold, the bus never came, the neighbours were at it again until two — you tell somebody, and you tell them with feeling.
The prepositions matter: you complain ABOUT the problem, TO the person who can fix it, and you complain OF a pain when you are talking to a doctor. In its formal use it means making an official report — complain to the council, complain in writing — and the noun is complaint, which covers both the act and an illness, as in a chest complaint. Can't complain is the standard English answer to how are you: things are fine, and saying so outright would be showing off. Calling someone a complainer is not a compliment.
1verbcomplainTo say that you are unhappy or annoyed about something.
“He complained that the room was too cold.”
2verbofficialTo make an official report about something that is wrong.
“She complained to the manager and got her money back.”
3verbpainTo say that you have a pain or an illness.
“He had been complaining of headaches for a week.”
Too few real examples of this word to estimate which sense is commonest.
Complain came through Old French complaindre from Medieval Latin complangere, 'to bewail', built from com-, 'together', and plangere, 'to strike or beat' — the beating being the beating of your own breast in grief. So the first complaints were not grumbles about cold soup but loud public mourning, done with the whole body.
Old French
complaindre
Middle English
complaynen
English, today
complain
Built from
From Middle English complaynen, from Old French complaindre. From Middle English complaynen, from Old French complaindre, from Medieval Latin complangere (“to bewail, complain”), from Latin com- (“together”) + plangere (“to strike, beat, as the breast in extreme grief, bewail”); see plain, plaint.
Etymology from Wiktionary, CC BY-SA