When the seller of a contract accepts the highest current price bid for a contract. For example, if the current market is in a Total Wins contract is 2.3 bid at 2.6, a trader may sell at 2.3, thereby "hitting" the best bid. (See Lift the Offer).
Seller's acceptance of the highest price offered for a stock. For example, if a stock's ask price is $24 1/4 and the current bid price is $24, sellers will hit the bid if they accept $24 a share. See: Asked Price