Exigent is a derivative of the Latin present participle of exigere, which means "to demand." Since its appearance in Middle English, the law has demanded a lot from exigent. It first served as a noun for a writ issued to summon a defendant to appear in court or else be outlawed. The noun's meaning was then extended to refer to other pressing or critical situations. Its adjectival sense followed and was called upon to testify that something was urgent and needed immediate aid or action. Nowadays, the adjective is seen frequently in legal contexts referring to "exigent circumstances," such as those used to justify a search by police without a warrant.