Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
tardĭtūdo, ĭnis, f. [tardus-pes], slowness, tardiness (ante-class. form for tarditas): podagrosi estis ac vicistis cochleam tarditudine, * Plaut. Poen. 3, 1, 29: segnes somno et tarditudine, Att. ap. Non. 181, 20 (Trag. Rel. v. 69 Rib.).