The adverb of supercilious: doing something in a way that shows you think you are better than the people around you. It tells you HOW an action was done, so it attaches to a verb — someone smiles superciliously, shrugs superciliously, answers superciliously, glances superciliously at your shoes. The behaviour it describes is quiet and cool rather than loud: the person is not being rude in any way you could report, but the look-down is unmistakable. Because of that, it goes most naturally with small physical actions and with ways of speaking, and it is much less common than the adjective. This is a written word — you will meet it in novels and in exam reading, where a writer wants to show a character's attitude without saying 'he was arrogant' straight out. In speech, people say 'he said it like he was better than us'.

傲慢地、輕蔑地（以瞧不起人的態度做某事，如「傲慢地笑了一下」）