Brúni is a weak variant of Brúnn, originally an Old Norse male byname meaning ‘brown’. The latter name is recorded in some Norwegian place-names, but the independent instances may be loans from Continental Germanic. The weak form of the name, Brúni, was the name of one of the original settlers of Iceland in Landnámabók ‘The Book of Settlements’, but this name soon dropped out of use in Norway. The weak form is common in Swedish runic inscriptions (as bruni) and occasionally appears in Denmark.
Brúni may be the first element in the place-name Brumby, Lincolnshire.
