Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
apprŏpinquātĭo (adp-), ōnis, f. [appropinquo], an approach (in time), drawing near (very rare; perh. only twice in Cic.): adpropinquatio mortis, Cic. Fin. 5, 11, 33 Baiter; so id. Sen. 19, 66: partus Faustinae, Marc. Aur. ap. Front. ad M. Caes. 5, 45.