Source : Webster's Revised Unabridged Dictionary (1913)

Jetsam \Jet"sam\, Jetson \Jet"son\, n. [F. jeter to throw: cf.
   OF. getaison a throwing. Cf. {Flotsam}, {Jettison}.]
   1. (Mar. Law) Goods which sink when cast into the sea, and
      remain under water; -- distinguished from flotsam, goods
      which float, and ligan, goods which are sunk attached to a
      buoy.

   2. Jettison. See {Jettison}, 1.