The word is derived from a Greek myth.
Narcissus was a handsome Greek youth who rejected the desperate advances of the nymph Echo.
As punishment, he was doomed to fall in love with his own reflection in a pool of water.
Unable to consummate his love, Narcissus pined away and changed into the flower that bears his name, the narcissus.
In psychology and psychiatry, excessive narcissism is recognized as a severe personality dysfunction or personality disorder, most characteristically Narcissistic personality disorder, also referred to as NPD.
Sigmund Freud believed that some narcissism is an essential part of all of us from birth and was the first to use the term in the reference to psychology.
Andrew Morrison claims that, in adults, a reasonable amount of healthy narcissism allows the individual's perception of his needs to be balanced in relation to others.
The concept of narcissism is used in evolutionary psychology in relation to the mechanisms of assortative mating, or the non-random choice of a partner for purposes of procreation.
Evidence for assortative mating among humans is well established; humans mate assortatively regarding age, IQ, height, weight, nationality, educational and occupational level, physical and personality characters and family relatedness.
In the “self seeking like” hypothesis, individuals unconsciously look for a mirror image of themselves in others, seeking criteria of beauty or reproductive fitness in the context of self-reference.
Some recent studies indicate that facial resemblance between couples was a strong driving force among the mechanisms of assortative mating: human couples resemble each other significantly more than would be expected from random pair formation.
Since facial characteristics are known to be inherited, the "self seeking like" mechanism may enhance reproduction between genetically similar mates, favoring the stabilization of genes supporting social behavior, with no kin relationship among them.