Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
nassĭterna (nāsĭt-), ae, f. [nasus], a large watering-pot with a large nose or spout: nassiterna est genus vasi aquarii ansati et patentis, quale est quo equi perfundi solent, Paul. ex Fest. p. 169 Müll.; Cato, R. R. 11; Varr. ap. Non. 546, 7; Plaut. Stich. 2, 2, 28.