1a tree, shrub, or herbaceous plant of the pea family, native to warm climates. Cassias yield a variety of products, including fodder, timber, and medicinal drugs (such as senna), and many are cultivated as ornamentals.
Genus Cassia, family Leguminosae: many species
2 (also cassia bark) [mass noun] the aromatic bark of an East Asian tree, yielding an inferior kind of cinnamon which is sometimes used to adulterate true cinnamon.
Cinnamomum aromaticum, family Lauraceae
Old English(in sense 2), from Latin, probably denoting the wild cinnamon, via Greek from Hebrew qĕṣī‘āh