Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
ĕlĕmentārĭus, a, um, adj. [elementum, II.], belonging to the elements or rudiments, elementary (post-Aug. and very rare): senex, an old schoolmaster, Sen. Ep. 36: litterae, elementary knowledge, Capitol. Pert. 1.