Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
nasturtĭum, ii, n. [nasi-tortium], a kind of cress: nasturtium nomen accepit a narium tormento, Plin. 19, 8, 44, § 155; cf. id. 20, 13, 50, § 127: (Persas) negat Xenophon ad panem adhibere quicquam praeter nasturtium, Cic. Tusc. 5, 34, 99; poet. in plur., Verg. M. 84; Col. poët. 10, 231.