Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
pĭātrix, īcis, f. [piator], she that appeases the gods by a sacrifice: piatrix dicebatur sacerdos, quae expiare erat solita, quam quidam simulatricem, alii sagam, alii expiatricem vocant, Fest. p. 213 Müll. (in Plaut. Mil. 3, 1, 101, read plicatricem).