A mark made by smearing.

“This detergent cleans windows without leaving smears.”

Any of various forms of distortion that make a signal harder to see or hear.

A Pap smear.

“I'm going to the doctor's this afternoon for a smear.”

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.”

To have a substance smeared on (a surface).

“She smeared her lips with lipstick.”

To damage someone's reputation by slandering, misrepresenting, or otherwise making false accusations about an individual, their statements, or their actions.

“The opposition party attempted to smear the candidate by spreading incorrect and unverifiable rumors about their personal behavior.”