IPA: /ˌsuːpəˈsɪlɪəsli/
KK: /ˌsuːpərˈsɪliəsli/
In a way that shows you think you are better than others; with an attitude of superiority.
She looked at him superciliously, as if he were beneath her.
Superciliously → It is formed from "superciliosus" (from Latin, meaning haughty or arrogant, literally 'eyebrowed', from "super-" meaning above and "cilium" meaning eyelid or eyebrow) and the adverbial suffix "-ly" (meaning in a manner of). The word describes behaving in a haughty or arrogant manner, as if looking down from above.
Think of someone acting 'above' ('super-') others, with an 'eyebrow' raised in disdain, which helps you remember that 'superciliously' means behaving arrogantly.