Syren, Syringa vulgaris, is ’lilac’. The word comes from Greek syrinx, ’water reed’, ’shepherd’s flute’. Ovid writes in his Metamorphoses that Syrinx was a nymph, daughter of the river Ladon. Once when the god Pan was out hunting he found the fair nymph and tried to rape her. The nymph fled and prayed her father for help. The help she got was to be transformed into a bunch of water reeds. Pan liked the sound of the wind in the reeds and from that day made his flutes of reeds. How this could give name to a bush with mauve flowers I haven't found out.
Lilac comes from French lilac from Spanish lilac, from Arabic lilak, from Persian lilak, ‘bluish’ from nil ‘indigo’.