Theodoric is a widespread Germanic given name. First attested in the 5th century, it became widespread in the Germanic-speaking world, not least due to its most famous bearer, Theoderic the Great, king of the Ostrogoths. The name was Latinized Theodoricus or Theodericus, originally from a Common Germanic form *þeudo-rīks ("people-ruler"), which would have resulted in a Gothic þiuda-reiks. Anglicized spellings of the name during Late Antiquity and the Early Middle Ages include Theodoric, Theoderic, Theudoric, Theuderic. Gregory of Tours Latinized the name as Theodorus, in origin the unrelated Greek name Theodore (Θεόδωρος, meaning "god-gift").
As the name survived throughout the Middle Ages, it transformed into a multitude of forms in the languages of Western Europe. These include the High German form Dietrich, abbreviated Dieter, the Low German and Dutch form Diederik, or Dierik, abbreviated Dirk, Diede, the patronymic Tietjens derived from the personal form Tietje, the Norwegian Tjodrik, and the French Thierry. Italian, Portuguese and Spanish have Teodorico.
The English forms Derek, Derrick and Terry have been re-introduced from the continent, from Low German, Dutch and French sources. The Welsh form Tudur is the origin of the name of the British Tudor dynasty.
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