Jetsam (ejected debris)

Word of the Day by James Somers:

flotsam, n. It's good to know the difference between flotsam ("FLOT-sum") and jetsam ("JET-sum"). Webster's explains that flotsam is "Goods lost by shipwreck, and floating on the sea," and jetsam is "Goods which sink when cast into the sea, and remain under water." Thus the distinction, in Webster's mind, is that flotsam floats and jetsam doesn't.

But the other important distinction is that flotsam is junk that unintentionally leaves the ship, whereas jetsam is jettisoned. OED: "...such material thrown overboard in order to lighten a vessel."

It's nice to have these terms at hand for their specific nautical uses, but more commonly they're used together, figuratively, to refer to random debris, as, "he was troubled all morning by half-dreams, the flotsam and jetsam of a strung-out mind."