Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
infortūnĭum, ĭi, n. [2. in-fortuna], misfortune (mostly ante-class. and post-Aug.; not in Cic. or Cæs.): ferres infortunium, thou wouldst come badly off, Ter. Ad. 2, 1, 24: ni pareat patri habiturum infortunium esse, * Liv. 1, 50, 9: invenire, Plaut. Am. 1, 1, 130: infortunio aliquem mactare, id. ib. 4, 2, 14: cavere infortunio, to guard against, id. Rud. 3, 5, 48; so, vitare, id. Cure. 2, 3, 19: domus alienae, App. M. 9, p. 228, 8: domus, id. ib. 9, p. 231, 22; 10, p. 241, 35; Macr. S. 7, 2, 5; 7, 3, 11; plur., App. de Dog. Plat. 2, p. 18, 3; Macr. S. 7, 2, 9.