Any of various shrubs or small trees of the genus Syringa (5)
I believe the answer is:
lilac
(Other definitions for lilac that I've seen before include "Shrub with fragrant purplish or white flowers" , "Tree - pinkish-purple colour" , "Pale violet hue" , "Shrub with fragrant pink, purple or white flowers" , "Pale mauve colour for a flower" .)