The OE masculine name Beorhthun was formed from the elements beorht, ‘bright, distinguished’ and hun, probably meaning ‘bear cub’. Derivation from the Continental Germanic equivalent, Berthund, though formally possible in onomastic terms, is extremely unlikely (von Feilitzen 1937: 194). It was evidently quite common earlier in Anglo-Saxon times, and is recorded in PASE as the name of seven individuals, all certainly or probably of high status, who lived from the late seventh century to the end of the ninth (PASE: Beorhthun 1–7). Thereafter it must have disappeared from use among the higher social ranks. Its unfamiliarity in the mid eleventh century may lie behind the addition of an unnecessary final –t in the DB spelling.
von Feilitzen 1937: Olof von Feilitzen, The Pre-Conquest Personal Names of Domesday Book, Nomina Germanica 3 (Uppsala: Almqvist and Wiksells, 1937)
Spellings in Domesday Book: Bertunt
Forms in modern scholarship:
von Feilitzen head forms: Beorhthun
Phillimore edition: Bertunt
Alecto edition: Beorhthun