Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
distortĭo, ōnis, f. [distorqueo], a distorting, writhing, contortion: membrorum, Cic. Tusc. 4, 13, 29; cf. id. Fin. 5, 12, 35: oris, Cels. 4, 2, 2.