The Early Modern English word for male bees was dore, (the etymological root of drone, another word for the male honeybee). To get the same effect of the drowsy, buzzing, summery sound of humming bees that bumblebee gives today, the previous incarnation of the word was, yes, Dumbledore. This was intentional on Rowlings part: Dumbledore has been said to have greatly loved music (particularly chamber music, according to his Chocolate Frog card), and she selected the name because it was easy to imagine everybodys favourite headmaster walking around, genially humming to himself in the summertime.