\Trag"a*canth\, n. [L. tragacanthum tragacanth,
tragacantha the plant producing tragacanth, Gr. ? ? a he-goat
+ ? a thorn: cf. F. tragacanthe.]
A kind of gum procured from a spiny leguminous shrub
({Astragalus gummifer}) of Western Asia, and other species of
Astragalus. It comes in hard whitish or yellowish flakes or
filaments, and is nearly insoluble in water, but slowly
swells into a mucilaginous mass, which is used as a
substitute for gum arabic in medicine and the arts. Called
also {gum tragacanth}.