Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
1. marrŭbĭum, ii, n., the plant horehound: marrubium quod Graeci prasion vocant, alii linostrophon, nonnulli philopaeda, aut philochares, Plin. 20, 22, 89, § 241; 14, 16, 19, § 105; Col. 10, 356.
2. Marrŭbĭum or Marrŭvĭum, ii, n.,