Lewis Short
cŏhortātĭo (noun 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.
Charlton T. Lewis, Charles Short, A Latin Dictionary