DIKE, or Dyke (Old Eng. dic, a word which appears in various forms in many Teutonic languages, cf. Dutch dijk, German Teich, Danish dige, and in French, derived from Teutonic, digue; it is the same word as "ditch" and is ultimately connected with the root of "dig"), properly a trench dug out of the earth for defensive and other purposes. Water naturally collects in such trenches, and hence the word is applied to natural and artificial channels filled with water, as appears in the proverbial expression "February fill-dyke," and in the names of many narrow waterways in East Anglia. "Dike" also is naturally used of the bank of earth thrown up out of the ditch, and so of any embankment, dam or causeway, particularly the defensive works in Holland, the Fen district of England, and other low-lying districts which are liable to flooding by the sea or rivers (see Holland and Fens). In Scotland any wall, fence or even hedge, used as a boundary is called a dyke. In geology the term is applied to wall-like masses of rock (sometimes projecting beyond the surrounding surface) which fill up vertical or highly inclined fissures in the strata.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)