Adjective. 1: without or bumps. 2: not rough. 3: without difficulties or problems. Example: it was a smooth transition. 4: without interruption. 5: without harshness. 6: not tasting unpleasant or sour. 7: a calm personality. Verb. 1: to remove the roughness or bumping us of something. 2: to iron out or remove creases in something. 3: to make something creamy. 4: to remove difficulties or problems with something. 5: to make things back better. Example: to smooth things over. 6: to remove electrical current irregularities.