Source : Webster's Revised Unabridged Dictionary (1913)

Supercilious \Su`per*cil"i*ous\, a. [L. superciliosus, fr.
   supercilium an eyebrow, pride; super over, + cilium an
   eyelid; probably akin to celare to conceal. Cf. {Conceal}.]
   Lofty with pride; haughty; dictatorial; overbearing;
   arrogant; as, a supercilious officer; asupercilious air;
   supercilious behavior. -- {Su`per*cil"i*ous*ly}, adv. --
   {Su`per*cil"i*ous*ness}, n.

Source : WordNet®

supercilious
     adj 1: having or showing arrogant superiority to and disdain of
            those one views as unworthy; "some economists are
            disdainful of their colleagues in other social
            disciplines"; "haughty aristocrats"; "his lordly
            manners were offensive"; "walked with a prideful
            swagger"; "very sniffy about breaches of etiquette";
            "his mother eyed my clothes with a supercilious air";
            "shaggy supercilious camels"; "a more swaggering mood
            than usual"- W.L.Shirer [syn: {disdainful}, {haughty},
             {lordly}, {prideful}, {sniffy}, {swaggering}]
     2: expressive of contempt; "curled his lip in a supercilious
        smile"; "spoke in a sneering jeering manner"; "makes many
        a sharp comparison but never a mean or snide one" [syn: {sneering},
         {snide}]