bid ‧ der /ˈbɪdə $ -ər/ BrE AmE noun [countable]
1 . someone who offers to pay a particular amount of money for something that is being sold:
The antiques will be sold to the highest bidder (=the person who offers to pay the most) .
2 . someone who offers to do work or provide services for a particular amount of money, in competition with others:
one of 13 bidders for the contract