The Collaborative International Dictionary of English v.0.48:

Mope \Mope\, v. i. [imp. & p. p. Moped; p. pr. & vb. n.
   Moping.] [Cf. D. moppen to pout, Prov. G. muffen to sulk.]
   To be dull and spiritless; to spend time doing little; as, to
   mope around the house. "Moping melancholy." --Milton.
   [1913 Webster]

         A sickly part of one true sense
         Could not so mope.                       --Shak.
   [1913 Webster]

WordNet (r) 3.0 (2006):

moped
    n 1: a motorbike that can be pedaled or driven by a low-powered
         gasoline engine