Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
grăvĭtūdo, ĭnis, f. [gravis], a cold in the head, catarrh (very rare): sine ructu et gravitudine, Apic. 3, 6, 76: arterica, Vitr. 1, 6, 3.