The Collaborative International Dictionary of English v.0.48:

Backwardation \Back`war*da"tion\, n. [Backward, v. t. + -ation.]
   (Stock Exchange)
   The seller's postponement of delivery of stock or shares,
   with the consent of the buyer, upon payment of a premium to
   the latter; -- also, the premium so paid. See Contango.
   --Biddle.
   [1913 Webster]