The Collaborative International Dictionary of English v.0.48:

Humblebee \Hum"ble*bee`\, n. [OE. humbilbee, hombulbe; cf. D.
   hommel, G. hummel, OHG. humbal, Dan. humle, Sw. humla; perh.
   akin to hum. [root]15. Cf. Bumblebee.] (Zool.)
   The bumblebee. --Shak.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Bumblebee \Bum"ble*bee`\, n. [OE. bumblen to make a humming
   noise (dim. of bum, v. i.) + bee. Cf. Humblebee.] (Zool.)
   A large bee of the genus Bombus, sometimes called
   humblebee; -- so named from its sound.
   [1913 Webster]

   Note: There are many species. All gather honey, and store it
         in the empty cocoons after the young have come out.
         [1913 Webster]

WordNet (r) 3.0 (2006):

humblebee
    n 1: robust hairy social bee of temperate regions [syn:
         bumblebee, humblebee]