Flotsam and Jetsam

flotsam n.

1. Goods floating on the surface of a body of water after a shipwreck or after being cast overboard to lighten the ship.
2. Discarded or unimportant things: “Keyrings, bookmarks … gum, scissors, paper clips … pencils and pads stolen from various hotels: all this detritus, this flotsam of a life being lived at full throttle” (David Leavitt).
3. People who are considered to be worthless or to have been rejected by society. flotsam AHD

jetsam n.

1. Goods that are cast overboard from a ship, especially in an attempt to lighten the ship, and that sink to the bottom of a body of water.
2. Discarded odds and ends. AHD jetsam

Dorian Krause

We almost always see flotsam and jetsam used as a complete phrase, typically in the context of the beach and the sea: “The flotsam and jetsam of the sea dotted the tide line.” That’s very much the way the phrase is used in this quotation from Robert B. Parker’s A Catskill Eagle:

Debris bumped against us as we edged along the pier. I didn’t look. I didn’t want to know what it was. The water was cold and harsh and black. There were barnacles here and there on the stones of the pier. Not many, and probably from another time. Not much could live in the water these days. Now and then half-rotten seaweed made the stones slimy and made me slip as we edged along.

Hawk said very softly, “You figure this stuff flotsam, or jetsam?”

As the AHD points out, in maritime law, flotsam refers to “Goods floating on the surface of a body of water after a shipwreck or after being cast overboard to lighten the ship.” Jetsam refers to cargo, supplies, or equipment deliberately thrown overboard from a ship in distress (including smugglers fearing legal ramifications) that floats or washes ashore and lands on the beach.
Lagan, a rather rare word today outside of maritime law, refers to items that are deliberately cast off from a ship and that and sink; traditionally, such items were tied to a buoy or float.

Legally, items considered jetsam and ligan belong to their original owner; flotsam may potentially be considered salvage. Items that are derelict are items that been abandoned.

Although the laws related to salvage and beaches are medieval in origin, they are still quite applicable today. In the United Kingdom, all four categories of debris are regulated by law and under the control of a Receiver Of Wreck. The Duke of Cornwall (AKA the Prince of Wales) has all right of wreck in the Duchy of Cornwall. That means, in broad terms, if you find something, you have to declare it, and the Duke has the right to claim it. Given the history of wrecks off the rocky, often dangerous shore of Cornwall, rights of wreck could have had fairly important ramifications in earlier eras.
Etymologically speaking, the wordflotsam came to Modern English via the Normans, and the Anglo-Norman floteson, from Old French floter, “to float,” of Germanic origin, and ultimately deriving from the Proto Indo-European root pleu-. *Flotsam, in English, was spelled flotsen until the middle of the nineteenth century, when it began to be spelled flotsam.

Jetsam was originally written jetson, from Middle English jetteson, cognate with Modern English jettison, to throw overboard. Lagan refers, technically, to an item attached to a float or buoy and thrown into the ocean, with the intention to retrieve it later. Etymologically, lagan derives from Old French, and (probably) from Old Norse lögn, lagn– which goes back to the Proto Indo-European root legh*- “to lie down,” the same root that gives us the Modern English verb “to lie” (down).

There are a surprisingly large number of idioms and phrases that are commonplace in Modern English, but which ultimately derive from legal terminology and, sometimes, the medieval equivalent of boiler plate text from legal documents. Flotsam and jetsam is one of those phrases.