tragacanthin
/traɡəˈkanθɪn/(also tragacanthine)
noun
Originally: a principal constituent of tragacanth and other gums, having the property of swelling in water (now disused ). Now: the water-soluble polysaccharide component of tragacanth.
Origin
Early 19th century; earliest use found in John Paris (bap. 1785, d. 1856), physician and author. From tragacanth + -in.