Source : Webster's Revised Unabridged Dictionary (1913)

Quintain \Quin"tain\, n. [F. quintaine, LL. quintana; cf. W.
   chwintan a kind of hymeneal game.]
   An object to be tilted at; -- called also {quintel}. [Written
   also {quintin}.]

   Note: A common form in the Middle Ages was an upright post,
         on the top of which turned a crosspiece, having on one
         end a broad board, and on the other a sand bag. The
         endeavor was to strike the board with the lance while
         riding under, and get away without being hit by the
         sand bag. ``But a quintain, a mere lifeless block.''
         --Shak.