DIKE, or Dyke, in its primary sense, denotes a ditch or drain. The word seems to have been formed from the verb to dig; though others derive it from the Dutch dijk, a dam, sea-bank, or wall. It is generally used to signify a work of stone, timber, or fascines, raised to oppose the entrance or passage of the waters of the sea, a river, lake, or the like. Junius and Ménage conceive the Flemish to have borrowed their word from the Greek πᾶχος, wall; but Guichard derives it from the Hebrew daghah.
Dyke is also a geological term denoting a mass of unstratified or igneous rock, such as trap, granite, or lava, which appears as if injected into rents and fissures in the stratified rocks. Veins of basalt, greenstone, &c., sometimes present the appearance of walls, standing detached on the surface of a country.