Floss is thin thread or cord used to clean between your teeth where your toothbrush can't reach. You wrap a piece of floss around your fingers, slide it gently between two teeth, and move it up and down to remove stuck food particles and plaque. Dentists recommend flossing daily because it helps prevent cavities and gum disease in those hard-to-reach spots.

Floss can also be a verb: when you floss your teeth, you're using dental floss to clean them. People also use the word playfully to mean showing off, as in flossing new sneakers or flossing a good grade, though this slang meaning is quite different from the dental kind.