Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
pistōrĭus, a, um, adj. [pistor], of or belonging to a baker, baker’s: opus pistorium, pastry, Cels. 2, 18; Plin. 18, 11, 27, § 105; Dig. 32, 1, 73 al.: ars, Vulg. Gen. 40, 17.