The Collaborative International Dictionary of English v.0.48:

Pot-bellied \Pot"-bel`lied\, a.
   Having a protuberant belly, like the bottom of a pot.
   [1913 Webster]

WordNet (r) 3.0 (2006):

potbellied
    adj 1: having a large belly [syn: abdominous, paunchy,
           potbellied]