Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
pernĭcĭābĭlis, e, adj. [pernicies], destructive, ruinous, pernicious: id perniciabile reo, Tac. A. 4, 34: nix oculis perniciabilis, Curt. 7, 3, 13: pestilentia quae magis in morbos longos quam in perniciabilis evasit, Liv. 27, 23, 7.