Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
intermissĭo ōnis, f. [intermitto], a breaking off, intermission, interruption; a neglecting, ceasing, discontinuance (class.): forensis operae, Cic. Div. 2, 68, 142: sine ulla intermissione, without any intermission, id. N. D. 1, 41, 114: a qua (actione) saepe fit intermissio, id. Off. 1, 6: per intermissiones has intervallaque, Liv. 5, 5: febris, Cels. 2, 10: epistularum, interruption of a correspondence, Cic. Fam. 7, 13, 1: consuetudinis, id. ib. 5, 17: intermissionem officii facere, id. Lael. 2, 8: si furiosus habet intermissionem, a lucid interval, Dig. 28, 1, 20: verborum, formed in short clauses, Cic. Part. 6.