Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
basterna, ae, f., a sedan chair or litter, enclosed on all sides, and carried by mules, Pall. 7, 2, 3; Lampr. Elag. 21; Amm. 14, 6, 16; Hier. Ep. 22 ad Eustoch. n. 16; cf. Isid. Orig. 20, 12, 5.