An Etymological Dictionary of the German Language/bellen
bellen, vb., from the equiv. MidHG. bëllen, OHG. bëllan, ‘to bark, bellow’; AS. bëllan, E. to bell (of a stag at the rutting period); the E. word indicates accordingly that the primary meaning was more general than simply ‘barking, bellowing.’ If an e root be assumed, OBulg. blěja, ‘bleat,’ and Lat. fleo, ‘I weep’ (b, f from bh and bhlê for bhel), may be compared. Others have explained the West Teut. root bell from belz, bels, bhels, which would result in its being cognate with Sans. bhaš, ‘to bark,’ bhâš, ‘to talk.’ Comp. Lith. bàlsas, ‘voice, tone’; see, too, the following word and Bulle.