Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
dētermĭnātĭo, ōnis, f. [determino], a boundary, conclusion, end: extrema ora et d. mundi, Cic. N. D. 2, 40, 101: exitus et determinatio orationis, id. Inv. 1, 52, 98.