Webster’s Revised Unabridged Dictionary · 1913
Shaster
Shas′ter, Shas′tra, n. [Skr. cāstra an order or command, a sacred book, fr. cās to order, instruct, govern. Cf. Sastra.] A treatise for authoritative instruction among the Hindoos; a book of institutes; especially, a treatise explaining the Vedas. [Written also sastra.]