is lilac a flower?
<answer> Yes, lilac is a flower. <context> Definition of lilac. 1  1a : a widely cultivated European shrub (Syringa vulgaris) of the olive family that has cordate ovate leaves and large panicles of fragrant pinkish-purple or white flowersb : a tree or shrub congeneric with the lilac. 2  2 : a variable color averaging a moderate purple.