Lexical Definition

‎συνείδω‎ syneídō (soon-i'-do) be aware ^G:V
from ‎σύν‎ and ‎εἴδω‎

consider, know, be privy, be ware of.

• to see completely
• used (like its primary) only in two past tenses, respectively meaning to understand or become aware, and to be conscious or (clandestinely) informed of

Abbott-Smith

** συν-εῖδον irreg. aor. of συνοράω (v.s. εἶδον), [in LXX: I Mac 4:21א, II Mac 2:24 4:4, 41 R 5:17 7:4, 20 8:8, III Mac 2:8 A * ;]
1. to see together or at the same time (Arist., Xen.).
2. to see in one view, hence, of mental vision, to comprehend, understand (LXX, Polyb., Plut., al.) : Ac 12:12 14:6 (on the related σύνοιδα, v. s.v.).†

Abbott-Smith References

Liddell-Scott-Jones

συνείδω,

perfect with present sense, 1st pers. plural σύνισμεν [Refs 5th c.BC+], Ionic dialect συνοίδαμεν [Refs 5th c.BC+], 3rd.pers. plural συνίσᾱσι [Refs 5th c.BC+]; infinitive ξυνειδέναι [Refs 5th c.BC+]pluperfect with imperfect sense, συνῄδειν, Attic dialect συνῄδη, dual συνῄστην, plural -ῇσμεν, -ῇστε, -ῇσαν, Ionic dialect2nd pers. plural συνῃδέᾰτε [Refs 5th c.BC+]: future συν (ξυν-) είσομαι [Refs 5th c.BC+], and aorist participle -ειδήσας[Refs 1st c.BC+]:—know something about a person, especially as a potential witness for or against him, ἢ (i.e. Δίκη) σιγῶσα σύνοιδε τὰ γιγνόμενα πρό τ᾽ ἐόντα [Refs 6th c.BC+]; τά τοι ἐγὼ καὶ ἀμφότερα συνειδὼς ἔχω μαρτυρέειν to both of which I, knowing them true of you, can testify, [Refs 5th c.BC+]; τὰ Μηδικὰ καὶ ὅσα αὐτοὶ σύνιστε our other services to which you can testify, [Refs 5th c.BC+]; ὑπολαμβάνων παρ᾽ ὑμῶν ἑκάστῳ τὸ συνειδὸς ὑπάρχειν μοι believing that I can rely on your acknowledgement of my services, [Refs 4th c.BC+]; τί μοι σύνοισθα τοιοῦτον εἰργασμέν; [συνείδω τῷ μειρακίῳ κοσμίῳ τὸν πρότερον ὄντι χρόνον ἀεί 4th-3rd c.BC: Menander Comicus “Σαμία” 57; πότερον οὐ συνοίδασιν αὐτῷ ποιοῦντι τὰ δίκαια 2nd c.BC: Polybius Historicus 27.9.11 ">Refs 5th c.BC+]; ξυνειδὼς οὐ φράσει; [συνείδω αὐτῷ 5th-6th c.BC: Xenophon Historicus “Memorabilia” 2.7.1 ">Refs 5th c.BC+]; οὐκ αἰσχυνοῦμαι.. εἰπεῖν (variant) ἅπασιν ὅσα σύνοιδ᾽ αὐτῷ κακά [Refs 5th c.BC+]; θνῄσκοντι συνείσῃ (conjecture Reiske for συνοίσῃ) thou wilt witness my death, [Refs 5th c.BC+]; δύ᾽ ἡμῶν ἢ τρία κακὰ ξυνειδὼς εἶπε δρώσας μυρία (i.e. Εὐριπίδης) [Refs 5th c.BC+]; καὶ τίνα σύνοισθά μοι καλουμένῃ βροτῶ; [Refs 4th c.BC+]; συνείδω τοῖς πλείστοις αὐτῶν ἥκιστα χαίρουσι I can bear witness that most of them are far from pleased.., [Refs 5th c.BC+]; with a mixture of dative and accusative construction, συνίσασι γὰρ αὐτῷ.. καθιστάμενον, ἐκ δὲ τούτων.. δυνάμενον [συνείδω 7th-6th c.BC: Sappho Lyrica 15 ">Refs 7th c.BC+]; ἐξ ὧν αὐτὸς σύνοισθα σαυτῷ ἐν τῇ τῶν γραμμάτων μαθήσει from your experience of yourself.., [Refs 5th c.BC+]; σύνοιδ᾽ ἐμαυτῇ πολλὰ (δείν᾽) [συνείδω 4th c.BC: Demosthenes Orator “Epistulae” 2.20; σ. ἑαυτοῖς ἄγνοιαν 4th c.BC: Aristoteles Philosophus “Ethica Nicomachea” 1095a25; σ. αὑτῷ τὴν δειλίαν [prev. author] “HA” 618a26; μηδὲν ἑαυτοῖς ἄτοπον συνειδέναι 5th-4th c.BC: Socratis et Socraticorum Epistulae cited in 5th c.AD: Stobaeus, Joannes 3.24.13, compare 5th-6th c.BC: Isocrates Orator 3.59, LXX.Job.27.6, NT.1Cor.4.4 ">NT+5th c.BC+]; συνειδότες αὑτοῖς with full consciousness, [Refs] W.:—with participle

__a in nominative, πῶς οὖν ἐμαυτῷ τοῦτ᾽ ἐγὼ ξυνείσομαι, φεύγοντ᾽ ἀπολύσας ἄνδρ; [συνείδω ἐμαυτῷ σοφὸς ὤν 5th-6th c.BC: Plato Philosophus “Apologia” 21b; ὅταν καὶ μηδὲν σαυτῷ συνειδῇς ἐξαμαρτάνων 5th-6th c.BC: Isocrates Orator 5.79. ">Refs 5th c.BC+]
__b in dative, συνείδω ἐμαυτῷ ἀντιλέγειν οὐ δυναμένῳ [Refs 5th c.BC+]
__2 with dative of things, know something about a thing, τοῖς διὰ τῶν εἰκότων τὰς ἀποδείξεις ποιουμένοις λόγοις συνείδω οὖσιν ἀλαζόσιν [Refs 5th c.BC+]; καιρὸς.. σὲ εἰπεῖν ἃ σύνοισθα τῷ βίῳ ἑκάστῳ what you know about each life, [Refs 2nd c.AD+]
__II share the knowledge of something with somebody, to be implicated in or privy to it, οὐδὲ ξυνῄδει σοί τις ἔκθεσιν τέκνο; [Refs 5th c.BC+]; ξύνοιδε δ᾽ οὔτις οἰκετῶν νόσον[Refs 5th c.BC+]; συνειδέναι δὲ (i.e. τὰς μαντηΐας) καὶ τοὺς Πυθίους [NT+5th c.BC+]participle
__II.a in dative, μήτε τῳ ξυνειδέναι τὸ πρᾶγμα βουλεύσαντι [Refs 5th c.BC+]
__II.b in accusative, ἀνδράποδα, ἂ συνῄδει τὴν γυναῖκα.. θάνατον μηχανωμένην [Refs 5th c.BC+]
__III know well, αὐτὸς ξυνειδώς, ἢ μαθὼν ἄλλου πάρ; as from his own knowledge, or.. ? [Refs 5th c.BC+]; so also (unless there is ellipse of reflexive pronoun) συνείδω δείν᾽ εἰργασμένος [Refs 5th c.BC+]
__IV with dative of things. to be privy to, [Refs 1st c.BC+]; τῷ φόνῳ [Refs 2nd c.AD+]
__V τὸ συνειδός complicity, τὸ σ. τοῦ πράγματος [Refs 1st c.AD+]; consciousness, τοῦ ἐνδεοῦς [Refs]
__V.2 conscience, ὑπὸ συνειδότος ἐπαρρησιάζετο ἀγαθοῦ [Refs 5th c.BC+]
__VI ὡς ἂν συνειδῇς as you may think proper, [Refs 6th c.AD+]

_{LSJ Scripture Refs: LXX.Job.27.6 ☩ 1Cor.4.4 ☩ Acts.5.2}