burn

\ \ [OE] English has two separate words burn.

\ \ The commoner, relating to ‘fire’, is actually a conflation of two Old English verbs: birnan, which was intransitive, and bærnan, which was transitive. Both come ultimately from the Germanic base *bren-, *bran-, which also produced brand and possibly broil, and was the source of German brennen and Swedish brinna ‘burn’ (another variant of the base, *brun-, lies behind the brim- of brimstone). It has been conjectured that Latin fervēre ‘boil’ (source of English fervent and ferment) may be connected. Burn ‘stream’ comes from Old English burn(e), burna, which was a descendant of a Germanic base *brun-, source also of German brunne ‘stream’. This too has been linked with Latin fervēre (from the notion of fast-running water ‘boiling’ over rocks).

\ \ Cf.⇒ BRAND, BRIMSTONE, BROIL, FERMENT, FERVENT