The Collaborative International Dictionary of English v.0.48:

Overbid \O`ver*bid"\, v. t.
   To bid or offer beyond, or in excess of. --Dryden.
   [1913 Webster]

WordNet (r) 3.0 (2006):

overbid
    n 1: a bid that is higher than preceding bids
    2: (bridge) a bid that is higher than your opponent's bid
       (especially when your partner has not bid at all and your bid
       exceeds the value of your hand) [syn: overbid, overcall]
    v 1: to bid for more tricks than one can expect to win,
    2: bid more than the object is worth [ant: underbid]