Definitions of smear:

• noun:   a thin tissue or blood sample spread on a glass slide and stained for cytologic examination and diagnosis under a microscope
• noun:   slanderous defamation
• noun:   an act that brings discredit to the person who does it
• noun:   a blemish made by dirt
• verb:   make a smudge on; soil by smudging
• verb:   stain by smearing or daubing with a dirty substance
• verb:   cover (a surface) by smearing (a substance) over it

  Example: "Smear the wall with paint"

• verb:   charge falsely or with malicious intent; attack the good name and reputation of someone