noun; a person who fancies himself/herself extraordinarily
intelligent, and well versed in one or many subjects, when, in reality, he/she is not. He/She is blinded by arrogance and self-righteousness. He/She will never think he/she is wrong, nor will he/she admit that someone else was right in retrospect. It is hard to maintain a
relationship with him/her, and he/she may even cause damage to the people around him/her because he/she is so caught up in his/her own opinions and ideas that he/she neglects to consider any other
possibility is valid.
adjective; marked by self-righteous arrogance and unjustified egotism