Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
prōclīnātĭo, ōnis, f. [proclino], a bending or inclining forwards: in concreto, a slope, declivity (Vitruvian), Vitr. 5, 12, 4.
In plur.: ne structurae habeant ullā in parte proclinationes, Vitr. 6, 11.