In maritime law, flotsam, jetsam, lagan and derelict are specific kinds of shipwreck. The words have specific nautical meanings, with legal consequences in the law of admiralty and marine salvage:
- Flotsam is floating wreckage of a ship or its cargo.
- Jetsam is part of a ship, its equipment, or its cargo that is purposely cast overboard or jettisoned to lighten the load in time of distress and that sinks or is washed ashore.
- Lagan (also called ligan) is cargo that is lying on the bottom of the ocean, sometimes marked by a buoy, which can be reclaimed.
- Derelict is cargo that is also on the bottom of the ocean, but which no one has any hope of reclaiming.