Source : Webster's Revised Unabridged Dictionary (1913)

Underbid \Un`der*bid"\, v. t.
   To bid less than, as when a contract or service is offered to
   the lowest bidder; to offer to contract, sell, or do for a
   less price than.

Source : WordNet®

underbid
     v 1: bid (a hand of cards) at less than the strength of the hand
          warrants
     2: bid lower than a competing bidder [ant: {outbid}]
     3: bid too low [ant: {overbid}]
     [also: {underbidding}]