Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
sējunctĭo, ōnis, f. [sejungo], a disjunction, separation, division (very rare): propositio, quid sis dicturus, et ab eo, quod est dictum, sejunctio (as a rhet. fig.), Cic. de Or. 3, 53, 203; cf. Quint. 9, 1, 28; 9, 2, 2; Flor. 1, 23, 2.