v. δέω, manquer.

subj. δέῃ, sts. contr. δῇ (in codd. of Com., as Ar. Ra. 265); ὁπόσου κα δῆ IG 4.1484.65 (Epid.), cf. SIG 245 G 47 (Delph.); opt. δέοι Th. 4.4; inf. δεῖν; part. δέον (v. infr. IV); impf. ἔδει, Ion. ἔδεε ; fut. δεήσει E. Hipp. 941, etc. ; aor.1 ἐδέησε Th. 2.77, etc.
Impers. from δέω¹, there is need (the sense of moral obligation, prop. belonging to χρή, is later, S. Ph. 583, etc.); c. acc. pers. et inf., it is needful for one to do, one must, once in Hom., τί δὲ δεῖ πολεμιζέμεναι… Ἀργείους why need the Argives fight? Il. 9.337; δ. <μ΄> ἐλθεῖν Pi. O. 6.28, etc. ; with nom. of the Pron., ἡγούμην… δεῖν… μεγαλοψυχότερος φαίνεσθαι D. 19.235; rarely δεῖ σ’ ὅπως δείξεις, = δεῖ σε δεῖξαι, S. Aj. 556, cf. Ph. 54; δεῖ σ’ ὅπως μηδὲν διοίσεις Cratin. 108; (the full constr. in S. Ph. 77 τοῦτο δεῖ σοφισθῆναι… ὅπως γενήσῃ); rarely c. dat. pers., there is need of… for…, θεοῖσι προσβαλεῖν χθονὶ ἄλλην δεήσει γαῖαν E. Hipp. 941, cf. X. An. 3.4.35, Oec. 7.20; the acc. pers. is often omitted, ἐκ τῶν μανθάνειν δεῖ (sc. ἡμᾶς) Hdt. 1.8, cf. A. Ag. 567, Eu. 826, etc. c. acc. rei et inf., δεῖ τι γενέσθαι Th. 5.26; παραδείγματα, καθ’ ἃ δέοι ἀποκρίνεσθαι Pl. Men. 79a, etc. ; also ἐπεὶ δέ οἱ ἔδεε κακῶς γενέσθαι since it was fated for him…, since he was doomed…, Hdt. 2.161, cf. 8.53, 9.109, S. OT 825; for οἴομαι δεῖν, v. οἴομαι. abs. with inf. understood, μὴ πεῖθ’ ἃ μὴ δεῖ (sc. πείθειν) S. OC 1442, cf. OT 1273; εἴ τι δέοι, ἤν τι δέῃ (sc. γενέσθαι), X. Mem. 1.2.59, Th. 1.44; κἂν δέῃ (sc. τροχάζειν), τροχάζῶ Philetaer. 3. c. gen. rei, there is need of, freq. with neg., οὐδὲν ἂν δέοι πολλοῦ ἀργυρίου Pl. Cri. 45a, etc. ; τί δεῖ τῆς ἀρετῆς; Arist. Pol. 1309b10; sts. with inf. added, μακροῦ λόγου δεῖ ταῦτ’ ἐπεξελθεῖν A. Pr. 870, cf. 875, Supp. 407. freq. in phrases, πολλοῦ δεῖ there wants much, far from it, ὀλίγου δεῖ there wants little, all but; in full c. inf., πολλοῦ δεῖ οὕτως ἔχειν Pl. Ap. 35d; τοὺς Πλαταιέας ἐλαχίστου ἐδέησε διαφθεῖραι [τὸ πῦρ] Th. 2.77; πολλοῦ γε δεῖ, πολλοῦ γε καὶ δεῖ Ar. Ach. 543, D. 18.300, 21.71; τοῦ πλεῦνος αἰεὶ ἔδεε there was always further to travel, Hdt. 4.43; τοῦ παντὸς δεῖ Luc. Merc. Cond. 13; also ὀλίγου δεῖν abs., in same sense, Pl. Ap. 22a, etc. ; μικροῦ δεῖν D. 27.29. with dat. pers. added, δεῖ μοί τινος A. Ag. 848, E. Med. 565, Th. 1.71, etc. with acc. pers. added, αὐτὸν γάρ σε δεῖ προμηθέως A. Pr. 86, cf. E. Rh. 837, Hipp. 23. rarely with Subj. in nom., δεῖ μοί τι something is needful to me, ἓν δεῖ μόνον μοι E. Supp. 594; εἴ τι δέοι τῷ χορῷ Antipho 6.12; πρῶτον μὲν τοῦτο δεῖ, ὑπειληφέναι… D. 10.15. Med., δεῖται there is need, c. gen., δεῖταί σοι τῆς αὐτῆς ἐρωτήσεως Pl. Men. 79c; ὅσων δέοιτο Aen.Tact. 13.1; ἑτέρου δεῖσθαι στρατηγοῦ νομίζων Plu. Pel. 26; c. inf., ὥστε βραχἔ ἐμοὶ δεῖσθαι φράσαι S. OC 570 (codd.); δεήσεται… ἀναγράφεσθαι Aen.Tact. 31.9; τήν μευ γλῶσσαν ἐκτεμεῖν δεῖται Herod. 6.41. neut. part. δέον (δεῖν is dub. in Ar. Fr. 220, Lys. 14.7, cf. A.D. Adv. 132.30, Hdn. Gr. 2.328, al., Hsch.); abs., it being needful or fitting, Pl. Prt. 355d, etc. ; οὐκ ἀπήντα, δέον, he did not appear in court, though he ought to have done so, D. 21.90; c. inf., Ar. Nu. 988; οὐδὲν δέον there being no need, Hdt. 3.65, etc. ; fut. ὡς αὐτίκα δεῆσον διώκειν X. Cyr. 3.2.8; aor. δεῆσαν Plu. Fab. 9, etc. ; also δέον ἂν εἴη, = δέοι ἄν, Plb. 2.37.5, etc. ; less freq. gen. abs. δέοντος, c. acc. inf., Corn. ND 17. Subst. δέον, τό (v. sub voc.).

s. δέω².

δεῖ impersonal (δέω),
[in LXX chiefly for infin. with לְ ;]
one must, it is necessary: with inf., Mat.26:54, Mrk.13:7, Act.5:29, al.; with accusative and inf., Mat.16:21, Mrk.8:31, Jhn.3:7, Act.25:10, al.; with ellipse of accusative, Mat.23:23; of accusative, and inf., Mrk.13:14, Rom.1:27 8:26; οὐ (μὴ) δεῖ (non licet), ought not, must not: Act.25:24, 2Ti.2:24; impf., ἔδει, of necessity or obligation in past time regarding a past event (Bl., § 63, 4), Mat.18:33, Luk.15:32, Jhn.4:4, Act.27:21, al.; periphr., δέον ἐστίν (as in Attic, χρεών ἐστι = χρή, see: δέον), Act.19:36; id., with ellipse of ἐστίν, 1Pe.1:6 τὰ μὴ δέοντα (= ἃ οὐ δεῖ 1Ti.5:13.
SYN.: ὀφείλει, expressing moral obligation, as distinct from δεῖ, denoting logical necessity and χρή, a need which results from the fitness of things (see Tr., Syn., § cvii, 10; Westc. on Heb.2:1, 1Jn.2:6; Hort on Jas.3:10). (AS)