Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
ēmendātrix, īcis, f. [emendator], she who corrects or amends: vitiorum emendatricem legem esse oportet, Cic. Leg. 1, 22, 58; id. Tusc. 4, 32, 69.