flotsam and jetsam

"Flotsam and jetsam" is a great phrase. With the satisfying way that it trips of the tongue, it's not surprising that it nearly always appears as a couplet. The two words are so often used together that I often forget that they have separate, specific meanings and that they are only two of seven such descriptors for sea borne debris.

• Derelict is: property abandoned at sea with no hope of recovery by the owner
• Flotsam is: property floating on the water that has been inadvertently lost - often after a shipwreck
• Jetsam is: property that is floating on the water after having been deliberately thrown overboard (jettisoned) - often to lighten the load in an attempt to avoid a shipwreck
• Ligan is: property sunk at sea but attached to a buoy for subsequent retrieval
• Ligsam is: any of Flotsam, Jetsam or Ligan
• Waveson is: property floating on the water that has been inadvertently lost - ONLY after a shipwreck
• Wreck is: property that has been washed ashore that may previously have been Derelict or Flotsam or Jetsam