blot

blotted; blotting; blots

A blot is a dirty smudge, mark, or stain, like the giant blot of ketchup that remains on your shirt long after the hotdog-eating contest is over.

A blot tends to mar or dirty a pristine surface, whether it's an ink blot on the book report you spent hours writing, or a blot of black paint on a white kitchen counter. Figuratively, a blot is something that dirties a person's reputation: "The scandal was a blot on the presidential campaign." As a verb, blot can mean "obscure," like when you use your hand to blot out the sun, or "dry a wet spot," the way you blot spilled tea with your napkin.