auction: the public sale of something to the highest bidder
transaction: the act of transacting within or between groups (as carrying on commercial activities)
albigensianism: a Christian movement considered to be a medieval descendant of Manichaeism in southern France in the 12th and 13th centuries; characterized by dualism (asserted the coexistence of two mutually opposed principles, one good and one evil); was exterminated for heresy during the Inquisition