Dirt, or a stain.
A chirp of radiation power from an astronomical body that has a smeared appearance on its plot in the time-frequency plane (usually associated with massive bodies orbiting supermassive black holes)
A stain on somebody's reputation.
To harm the reputation of; to smear or slander.
To dirty; to make dirty.
A blot or splash.
To move in a manner that causes splashing or spreading of material.
To manipulate roughly or crudely.
To mark with a splatch.