thoro- combining form ['Ɵɔ:rǝʊ] of THORIUM: see -O-.

■ thoro'gummite noun [GUMMITE] Mineralogy a tetragonal basic silicate of thorium, usu. also containing uranium, and occurring as microcrystalline aggregates, usu. yellowish-brown or greenish-grey L19.

■ Thorotrast noun [CON)TRAST noun] Medicine (US proprietary name for) a colloidal solution of thorium dioxide used (esp. formerly) as a contrast medium in radiography M20.

[TahlilGaran] English Dictionary ▲