Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
dispŭtātrix, īcis, f. [disputator], a female disputant, one given to disputation: etiam virtus erit, Quint. 2, 20, 7; as the Lat. equivalent of διαλεκτική (sc. τέχνη), the art of disputing, id. 12, 2, 13.