The Collaborative International Dictionary of English v.0.48:
Self-important \Self`-im*por"tant\, a. Having or manifesting an exaggerated idea of one's own importance or merit. [1913 Webster]WordNet (r) 3.0 (2006):
self-important adj 1: having or showing feelings of unwarranted importance out of overbearing pride; "an arrogant official"; "arrogant claims"; "chesty as a peacock" [syn: arrogant, chesty, self-important]