Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
improspectus (inpr-), a, um, adj. [2. in-prospectus], not seen from afar, unseen: Aetna, Auct. Carm. Aetn. 339.
Adv.: improspectē, improvidently: Jephte improspecte voverat, Hier. adv. Jovin. 1, 23: satis, Tert. Anim. 24.