with or by force:
I.act. constraining, applying force, Il.; ἦμαρ ἀν. the day of constraint, i. e. slavery, Ib.;so, ἀναγκαία τύχη the lot of slavery, or a violent death, Soph.; τῶι τῆς ἀρχῆς ἀναγκαίωι by the compulsory nature of our rule, Thuc.; ἐξ ἀναγκαίου under compulsion, id=Thuc.
2.of arguments, forcible, cogent, id=Thuc.
II.pass. constrained, forced, πολεμισταὶ ἀν. soldiers perforce, whether they will or no, Od.
2.necessary, ἀναγκαῖόν [ἐστι], like ἀνάγκη ἐστί, c. inf., it is necessary to do a thing, Hdt., etc.; but, ἔνιαι τῶν ἀποκρίσεων ἀναγκαῖαι ποιεῖσθαι necessarily requiring to be made, Plat.
3.τὰ ἀναγκαῖα necessary things, needs, as food, sleep, id=Plat., Xen.; τὰ ἐκ θεοῦ ἀν. the appointed order of things, laws of nature, id=Xen.
4.absolutely necessary, indispensable, barely sufficient; ἀν. τροφή ῀ ἡ καθ᾽ ἡμέραν, Thuc.; τὸ ἀναγκαιότατον ὕψος the least height that was absolutely necessary, id=Thuc.; ἡ ἀναγκαιοτάτη πόλις the least that could be called a city, Plat.
5.of persons, connected by necessary ties, i. e. related by blood, id=Plat., etc.:— οἱ ἀναγκαῖοι, Lat. necessarii, kinsfolk, Xen., etc.