Spraint is a piece of otter's dung.
photo by Ed Bowlby
No, it's not the sort of thing you trip over every day - which is good, because it's dark, tar-like, smelly stuff.
The most amusing thing about this word, I think, is that it comes from the same source as the word espresso.
Word To Use Today: spraint. This word comes from the Medieval French espraintes, from espreindre, to press out.