Back in the day, bumblebees used to be called humble-bees.  That’s not because people found the insects to be particularly modest; it is for the same reason we now call them bumblebees.  The bumble or humble refers to the buzzing sound the bees make.  Bumblebees are classified in the bee genus Bombus, which from Latin translates roughly to “hum or buzz.”  Check this.  In Middle English, “dumbledore” was the word for bumblebee.  Dumbledore is also the name of the headmaster in the Harry Potter books.  J.K. Rowling imagined that Professor Dumbledore walked around humming all the time, sounding much like a bumblebee.  Holy crap.  How annoying would it be to have Dumbledore hanging around?  Always humming.  Just being all old.  Humming all the time.