Fewmet or fumet is an archaic term for the droppings of a hunted animal, especially a deer. It comes from the French fumer, the verb meaning 'to drop dung'.
This word remains with us primarily because it was used in T. H. White's novel The Once and Future King, when King Pellinore used fewmets to hunt the Questing Beast. Because of this, it is often used in fantasy novels to refer to dragon droppings, appearing in Madeleine L'Engle's A Wind in the Door and The Harvard Lampoon's Bored of the Rings ("The halberd has fallen! The fewmets have hit the windmill!"), and is used as a swearword in both Anne McCaffrey's Dragonriders of Pern novels and Jane Yolen's Pit Dragon Chronicles. In the roleplaying game The Fantasy Trip, fewmet was also used to refer to dragon droppings, and was used to make black powder for grenades, a meme which has stuck in gaming circles.
It was, and is, almost always used in the plural, fewmets.