(transitive, law) to formally demand (that someone do or refrain from doing something), generally with a threat of litigation if the demand is not complied with; to send a formal demand letter (mise en demeure) to; to give notice of a legal obligation, time limit, etc., so that unawareness of it cannot be alleged / (transitive, figurative) To demand that someone do or not do something; to order or insist vigorously or peremptorily.