to sell something [to the highest bidder] at an auction. He auctioned his home off.He auctioned off his home.The duke was forced to auction off his ancestral home to pay his taxes.
To sell something to the person who offers the highest amount of money, at or as at an auction: We don't need this table anymore, so we should auction it off. To clear out the warehouse, the company auctioned off the old inventory.