Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
cŏhortātĭo, ōnis, f. [cohortor], an exhorting, inciting; exhortation, encouragement (rare, but in good prose): militum, Nep. Hann. 11, 1: legionis, Caes. B. G. 2, 25: Caesaris, Auct. B. Alex. 22: ducis, Tac. A. 14, 30: judicum, Cic. Clu. 50, 138: incredibiliter me commovet tua cohortatio, id. Att. 16, 13, C, 2; so id. Fam. 1, 7, 9; id. de Or. 1, 47, 204: his cohortationibus, id. ib. 1, 61, 262.