Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
illīsĭo (inl-), ōnis, f. [illido], a striking or dashing against (late Lat.): scopulorum, Hier. Ep. 43, 3: dentium, Cael. Aur. Tard. 1, 4, 65.