Narcissus

Narcissus was the son of the river Cephissus and the nymph Liriope, a beautiful boy who, having repulsed the love of many men and women, fell in love with his own reflection in a pool on Mount Helicon and gradually wasted away and died, whereupon the gods turned him into the flower that bears his name. There has been some dispute as to whether the flower took its name from him or the other way round.

Pliny wrote that the name of the flower derived 'not from the boy in the myth' but from narce, 'stupor', as it had the power of 'burdening the head'. The numbing power that the plant was alleged to have can be seen reflected in the English 'narcotic'.

So perhaps the best interpretation of the name is 'benumbed', alluding both to the plant and its power and to the 'benumbed' state of the boy as he pined away. The -issus ending of his name (also seen in that of his father), like the element -nth- (in Hyacinthus, for example, another good-looker), indicates that the name is probably not Greek at all.