Something that is inappropriate is not justified or often right. The term “unreasonable delay” is common and means that someone has to wait far too long for something, whether it`s a building permit or a dentist appointment. The adjective means “not due” or “not payable” since its original definition in the fourteenth century. If something is inappropriate or justified, you can call it inappropriate. For example, an unreasonable delay in a hospital waiting room can be dangerous for a person who has suffered a serious injury.