'narcissistic' originates from Greek, specifically the word 'Narkissos', where the name referred to the mythological youth 'Narcissus' (and the flower associated with him).

'narcissistic' changed from Greek 'Narkissos' into Latin 'narcissus', entered modern European languages (via Late Latin and French), and the psychological noun 'narcissism' was formed in the 19th century; the adjective 'narcissistic' was then formed from 'narcissism' + the suffix '-ic'.

Initially it referred to the mythological figure (or the flower named for him); over time it evolved to mean excessive self-love or self-admiration and traits related to such behaviour (including the clinical sense in psychology).