a dirty mark with no clear shape synonym smear a smudge of lipstick on a cup Word Origin late Middle English (as a verb in the sense ‘soil, stain’): of unknown origin. The noun dates from the late 18th cent.Extra examples She had dark smudges under her eyes from too many sleepless nights. The boat was just a grey smudge on the horizon. She pushed back her hair, leaving a smudge of paint on her face. There was a smudge of lipstick on the cup.