Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
littĕrālis (lītĕr-), e, adj. [littera], of or belonging to letters or writing (postclass.): commercium, epistolary correspondence, Symm. Ep. 4, 52: lectio, the reading of books, Cael. Aur. Tard. 1, 5: grammatica litteralis dicta, quod a litteris incipiat, Diom. p. 414 P.