C2[C]something that controls what you do by keeping you within particular limits: The constraints of politeness wouldn't allow her to say what she really thought about his cooking.Financial constraints on the company are preventing them from employing new staff.Limiting and restrictingPreventing and impeding›[U]formalunnatural behaviour that is sometimes the result of forcing yourself to act in a particular way: She tried to appear friendly, but her constraint was obvious.Self-control and moderationunder constraintformal›If you do something under constraint, you do it only because you have been forced to: They confessed, but only under severe constraint.Duty, obligation and responsibility