An affix used in names to denote a @C00770@ or closed structure, especially a boron skeleton that is a polyhedron having all triangular faces.
Sources: Blue Book, p. 464 [Terms] [Book] PAC, 1972, 30, 681. (Nomenclature of Inorganic Boron Compounds) on page 686 [Terms] [Paper] Red Book, 3rd ed., p. 245 [Terms] [Book]