arrogant

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Having or displaying a sense of overbearing self-worth or self-importance.
• adjective Marked by or arising from a feeling or assumption of one's superiority toward others.

from The Century Dictionary.

• Making or having the disposition to make unwarrantable claims of rank or estimation; giving one's self an undue degree of importance; aggressively haughty; full of assumption: applied to persons.
• Characterized by arrogance; proceeding from an overestimate of one's importance or superiority to others: applied to things: as, arrogant claims.
• Synonyms Authoritative, Magisterial, Dogmatic, etc. (see magisterial), proud, assuming, overbearing, presumptuous, supercilious, lordly, cavalier, important, swelling, blustering, grand, disdainful, overweening.

from the GNU version of the Collaborative International Dictionary of English.

• adjective Making, or having the disposition to make, exorbitant claims of rank or estimation; giving one's self an undue degree of importance; assuming; haughty; -- applied to persons.
• adjective Containing arrogance; marked with arrogance; proceeding from undue claims or self-importance; -- applied to things.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective Having excessive pride in oneself, often with contempt for others.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• adjective having or showing feelings of unwarranted importance out of overbearing pride