Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
mŏlārĭus, a, um, adj. [mola], of or belonging to a mill or to grinding, mill- (anteclass.): asinus molarius, a mill-ass, an ass that turns a mill, Cato, R. R. 11, 4; Varr. R. R. 1, 19, 3.