: a dirty mark, spot, streak, etc., made by touching or rubbing something
medical : a very small sample of something (such as skin or blood) that someone examines with a microscope
: an untrue story about a person that is meant to hurt that person's reputation
: to make (something) dirty by rubbing it with something else
: to spread (something) over a surface
: to spread or drip in an untidy way
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