Narcissus is the botanic name for the flower more commonly known in English as the daffodil. Its name was either taken from or given to the Narcissus of Greek myth who, unwittingly falling in love with his own image, pined his life away beside the pool which reflected it. 'Narcissism' was coined as a term for pathological self-love by criminal psychologist Paul Näcke, and later adopted into Freud's portrait of the mind as a trait present in the development of all personalities.
Online edition of Ovid's 'Metamorphoses', as translated by Sir Samuel Garth, John Dryden, et al (1st-century AD)
Online edition of Freud's essay 'On Narcissism', as translated by James Strachey, (1914)