1. To spread or daub some substance onto someone or something. I came into the kitchen and saw that our toddler had smeared the walls with chocolate. The leader smeared the warriors with paint to intimidate their foes.

2. To damage or attempt to ruin someone's or something's reputation through the perpetuation of claims or rumors about their failures or faults, whether these are true, exaggerated, or falsified. The president's reelection campaign has already begun smearing her opponent. The company argued that its competition had been trying to smear their reputation with false claims about using sweatshop labor in their manufacturing process.