Narcissism is a term that originated with Narcissus in Greek mythology who fell in love with his own image reflected in a pool of water. Currently it is used to describe a person characterized by egotism, vanity, pride, or selfishness.
Such a person may appear attractive initially but you would have a terrible headache when you start to know them better or need to work with them. Here are some personality traits that objective people will see but he would flatly deny:
a. Problems in sustaining satisfying relationships.
b. Difficulty with empathy.
c. Detesting those who do not admire them (narcissistic abuse).
d. Using other people without considering the cost of doing so—exploitation.
e. Pretending to be more important than they really are.
f. Bragging (subtly but persistently) and exaggerating their achievements.
g. Inability to view the world from the perspective of other people.
h. Denial of remorse and gratitude. - A Psychologist