An emissary (Latin emissarium, from ex and mittere, to send out) is a channel, natural or artificial, by which an outlet is formed to carry off any stagnant body of water. Such channels may be either open or underground; but the most remarkable works of the kind are of the latter description, as they carry off the waters of lakes surrounded by hills. The need for emissaries did not cease with Antiquity, of course, and modern examples abound. The initial text of this article was an abridgment from Smith's Dictionary of Greek and Roman Antiquities (1875 edition, public domain).