(Bot.) A perennial suffrutescent plant (Ruta graveolens), having a strong, heavy odor and a bitter taste; herb of grace. It is used in medicine. "Then purged with euphrasy and rue The visual nerve, for he had much to see." "They (the exorcists) are to try the devil by holy water, incense, sulphur, rue, which from thence, as we suppose, came to be called herb of grace."