What is Bid Off?

Legal Definition
One is said to "bid off" a thing when he bids for it at an auction sale, and it is knocked down to him in immediate succession to the bid and as a consequence of it. Ep-pes v. Railroad Co., 35 Ala. 56; Doudna v. Harlan, 45 Kan. 484, 25 Pac. 883.
-- Black's Law Dictionary