noun a light purplish color like that of the flower of the purplish lilac.
2. lilac ·noun a shrub of the genus syringa. there are six species, natives of europe and asia. syringa vulgaris, the common lilac, and s. persica, the persian lilac, are frequently cultivated for the fragrance and beauty of their purplish or white flowers. in the british colonies various other shrubs have this name.