1.to force, compel, mostly c. acc. pers. et inf., ἀν. τινὰ ποιεῖσθαι τι, λέγειν, etc., Hdt., etc.:—so Pass., ἠναγκάζοντο ἀμύνεσθαι id=Hdt.;—without the inf., ἀναγκάζεσθαί τι to be forced to do a thing, Plat., etc.:—also, ἀναγκάζειν τινὰ ἔς τι Thuc.
2.c. acc. pers. only, to constrain by argument, Plat.: Pass., ἠναγκάσθην I was constrained, tortured, Soph.; ἠναγκασμένος, ἀναγκασθείς under compulsion, Thuc.
3.c. acc. rei only, to carry through by force, Eur.
4.c. acc. rei et inf. to prove that a thing is necessarily so and so, Plat.