The origin of this surname is found in the office of 'judex' or 'dempster' to the Parliament, shire, or baron-bailie. Until the year 1747 every laird whose land had been erected into a barony was empowered to hold courts for the trial and punishment of certain offenders within his barony; and the dempster was part of his retinue. The name of Haldan de Emester of Perthshire, who rendered homage in 1296 (Bain, II, p. 200), is to be read Haldan Deem ester. Andrew Dempstar made a gift of his lands of Menmuir to the Priory of Restennot, 1360, and witnessed a Brechin document in 1364 (REB., I, 21). In 1370, as dominus de Keraldstoun, he had a charter of the office of dempster from the Abbot of Arbroath to himself and his heirs (RAA., II, p. 31), and in 1379 the office of judex in parliament and justiciar in courts in the sheriffdom of Forfar was also confirmed to him and his heirs by Robert II (RMS., I, 758). Robert Demster was bailie of Forfar, 1361 (ER., II, p. 62). David Dempster of Careston was one of the perambulators of marches near Arbroath, 1370 RAA. I, p. 31,114), Androw Dempstar was on the assize of the marches of Woodwrae, 1388 (Bamff, p. 22), and Henry Demstar was one of an inquest made at Edinburgh, 1428 (RAA., II, 61). Matho Dempstar and Andro Dempstar were burgesses of Brechin, 1579 (RPC., III, p. 202), caution was found for Thomas Dempstare of Cushnie, 1585 (ibid., p. 732), Alexander and William Dempstar and other 'broken' Moray men assisted the Macdonalds of Glencoe in a raid in Moray, 1602 (ibid., VI p. 431), and Bessie Demster is recorded in the parish of Rerrick, 1684 (ibid., 3. ser. LX, p. 573). Thomas Dempster (d. 1625), historian, and George Dempster (1755—1818) of Dunnichen, the agriculturist, were two of the more distinguished of the name. The Historia Ecclesiastica of Thomas Dempster has been described as "probably the most untrustworthy book upon Scottish literature ever written' (Geddes, Bibliography of Middle Scots poets, p. xvii).

= Deem (q.v.) + the agent (orig. fem.) suff. ~ster, Old English -estre.

The Manx judges are still called Dempsters or Deemsters.

A judge; the officer of a court who pronounces doom. Anglo-Saxon deman, to judge. Jamieson. The Isle of Man is divided into two districts, over each of which a deemster still presides. Before the Union, there was an officer in the Scottish senate called the Dempster of Parliament, probably corresponding with the English "Speaker." This office was hereditary in the ancient family of Dempster of Auchterless, and hence their surname. In the old M.S. poem called Cursor Mundi, quoted by Halliwell, we read: —

An arbitrator.

Anciently an arbitrator or officer of justice in the Scottish courts.

Dempster: a Deemster, Member of Parliament in the Isle of Man and in Scotland. Deemer, Deamer, and with intrusive r, Dearmer.