In maritime law, there are four types of marine debris: flotsam (floating goods that were not deliberately thrown overboard), jetsam (floating goods that were intentionally discarded), lagan (sunken goods that are tied to a floating object), and derelict (unrecoverable sunken goods). Of those, flotsam and jetsam have been repurposed by the public as an irreversible binomial that means "discarded or useless objects" in general. The words are essentially equivalent to float and jettison: flotsam comes from Old French flotaison (or "floating"), which traces to Frankish flotan, meaning "swim", Proto-Germanic flutona, and Proto-Indo-European plow, "to flow"; and jetsam is from Old French getaison ("throwing"), which in turn probably derives from the Latin verb iactare, meaning "to throw".
Hello! I'm Adam Aleksic, a junior studying government and linguistics at Harvard University, where I co-founded the Harvard Undergraduate Linguistics Society. In addition to etymology, I also really enjoy trivia, politics, vexillology, geography, board games, conlanging, art history, and law.