A hedge, an inclosure, to inclose, fence in, a protection, a place of safety. In Dutch, Haag; Sax., Hege; Ger., Heck; Danish, Hekke; Swedish, Hagn; Fr., Haie; Welsh, Cae; Gaelic, Ca; Cor. Br., Hay. "In the reign of Kenneth III. (says Douglass), about 980, the Danes having invaded Scotland, were encountered by that king, near Loncarty, in Perthshire. The Scots at first gave way, and fled through a narrow pass, where they were stopped by a countryman of great strength and courage, and his two sons, with no other weapons than the yokes of their plows. Upbraiding the fugitives for their cowardice, he succeeded in rallying them; the battle was renewed, and the Danes totally discomfited. It is said, that after the victory was obtained, the old man, lying on the ground wounded and fatigued, cried 'Hay, Hay,' which word became the surname of his posterity. The king, as a reward for that signal service, gave him as much land in the Carse of Gowrie as a falcon should fly over before it settled; and a falcon being accordingly let off, flew over an extent of ground six miles in length, afterward called Errol, and lighted on a stone still called Falconstone or Hawkstone."

Arthur, William (1857) An Etymological Dictionary of Family and Christian Names. New York: Sheldon, Blakeman. Public Domain.

HAY. A-Sax. haeg, Fr. haie, a hedge, and that which it encloses— a field or park. The map of Normandy shows many localities called La Haie, and from one of these, doubtless, came, in early Norman times, if not actually at the Conquest, the family once eminent in England and still so in Scotland. The name Avas written De Haia and De la Hay. KingHenrj'I. gave to Robert de Haia the lordship of Halnaker, co. Sussex, and so early as the close of the XII. cent. William de H. passed into Scotland and held the office of pincerna regis or king's butler, temp. William the Lion. From his two sons descend Hay, marquis of Tweeddale, and Hay, earl of Errol, hereditary lord high constable of Scotland. Tliese are well-ascertained facts, but tradition assigns a difterent origin both to name and family. It asserts that in 980 a yeoman called John de Luz and his two sons by their prowess reinvigorated the anny of Kenneth IIL, when they were on the point of succumbing to the Danes. They took the yokes from the oxen with which they were iloughing. and so belaboured the invaders as to drive them from the field, amidst shouts of Hay! Hay! Tlie king in reward for these services gave the yeoman as much laud as a falcon could fly round (the lands of Loncarty near Fife), and in memory of the event the family adopted a falcon for their crest, two husbandmen with ox-yokes for their supporters, and Hay for their surname !

Lower, Mark A (1860) Patronymica Britannica: a dictionary of the family names of the United Kingdom. London: J.R. Smith. Public Domain.