Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
frustrātĭo, ōnis, f. [frustror], a deceiving, deception, disappointment, frustration (rare; not used by Cicero): in horunc familiam Hodie frustrationem iniciam maximam, Plaut. Am. 3, 1, 15; so, frustrationes dare (with ludificare), id. Most. 5, 2, 30: clamant, fraude fieri, quod foris teneatur exercitus: frustrationem eam legis tollendae esse, Liv. 3, 24, 1: cum longo sermone habito dilatus per frustationem esset, id. 25, 25, 3.
With subj. gen.: frustratio Gallorum eo spectabat, ut tererent tempus, donec, etc., id. 38, 25, 7.
In plur.: cum variis frustrationibus differretur, Just. 9, 6: quo magis me petiverunt, tanto majorem iis frustratio dolorem attulit, failure, Planc. ap. Cic. Fam. 10, 23, 5; Quint. 2, 20, 3: sine successu ac bono eventu frustratio est, non cultura, failure, Varr. R. R. 1, 1, 6.