verb

• (transitive) To spread (a substance, especially one that colours or is dirty) across a surface by rubbing.
  "The artist smeared paint over the canvas in broad strokes."
• (transitive) To cover (a surface with a layer of some substance) by rubbing.
  "She smeared her lips with lipstick."
• (transitive) To make something dirty.
  "A man may bee smeared or grimed, and euerie man shall laugh at him, and yet he himselfe shall not perceiue it a whit."
• (transitive) (of a substance, etc.) To make a surface dirty by covering it.
  "a pallor which was accentuated by the blood which smeared her lips and cheeks and chin"

noun

• (countable, uncountable) A false or unsupported, malicious statement intended to injure a person's reputation.
  "smear campaign"
• (biology) A preparation to be examined under a microscope, made by spreading a thin layer of a substance (such as blood, bacterial culture) on a slide.
• (medicine) A Pap smear (screening test for cervical cancer).
  "I'm going to the doctor's this afternoon for a smear."
• (radio, television, uncountable) Any of various forms of distortion that make a signal harder to see or hear.
  "In television terms, a certain amount of smear, ringing, and anticipatory overshoot are indigenous to VSB transmission."