Gromwell \Grom"well\, n. [Called also gromel, grommel, graymill, and gray millet, all prob. fr. F. gr?mil, cf. W. cromandi.] (Bot.) A plant of the genus {Lithospermum} ({L. arvense}), anciently used, because of its stony pericarp, in the cure of gravel. The {German gromwell} is the {Stellera}. [Written also {gromill}.]