From ana and the base of agkale; constraint (literally or figuratively); by implication, distress -- distress, must needs, (of) necessity(-sary), needeth, needful.
see GREEK ana
see GREEK agkale
1. necessity, imposed either by the external condition of things, or by the law of duty, regard to one's advantage, custom, argument: κατ' ἀνάγκην perforce (opposed to κατά ἑκούσιον), Philemon 1:14; ἐξ ἀνάγκης of necessity, compelled, 2 Corinthians 9:7; Hebrews 7:12 (necessarily); ἔχω ἀνάγκην I have (am compelled by) necessity, (also in Greek writings): 1 Corinthians 7:37; Hebrews 7:27; followed by an infinitive, Luke 14:18; Luke 23:17 R L brackets; Jude 1:3; ἀν. μοι ἐπίκειται necessity is laid upon me, 1 Corinthians 9:16; ἀνάγκη (equivalent to ἀναγκαῖον ἐστι) followed by an infinitive: Matthew 18:7; Romans 13:5; Hebrews 9:16, 23 (also in Greek writings).
2. in a sense rare in the classics (Diodorus 4, 43), but very common in Hellenistic writings (also in Josephus, b. j. 5, 13, 7, etc.; see Winers Grammar, 30), calamity, distress, straits: Luke 21:23; 1 Corinthians 7:26; 1 Thessalonians 3:7; plural ἐν ἀνάγκαις, 2 Corinthians 6:4; 2 Corinthians 12:10.