Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
dissŏcĭātĭo, ōnis, f. [dissocio], a separation (post-Aug.), Plin. 6, 1, 1, § 2; 7, 13, 11, § 57; Tac. A. 16, 34.