Source : Webster's Revised Unabridged Dictionary (1913)

Tragacanth \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}.

Source : WordNet®

tragacanth
     n : a gum used in pharmacy, adhesives, and textile printing