the Lilac, in botany: A genus of plants belonging to the class of diandria, and order of monogynia; and in the natural system ranging under the 44th order, Separia. The corolla is quadrifid, and the capsule is bilocular. There are three species, the vulgaris, persica, and fufsenia. The two first are natives of Persia, and the last of Japan.—The vulgaris, which is distinguished by ovate heart-shaped leaves, was cultivated in Britain about the year 1597 by Mr John Gerard.—The persica, which has lanceolate leaves, was cultivated in 1658; but how long both species might have been introduced into Britain before these dates, it is perhaps impossible to ascertain.