Quick Definition
consequently, therefore
Strong's Definition
truly for then, i.e. consequently
Derivation: from G5104 (τοί) and G1063 (γάρ) and G3767 (οὖν);
KJV Usage: there-(where-)fore
Thayer's Greek Lexicon
τοιγαροῦν (from the enclitic τοι or τῷ, γάρ, and οὖν, German doch denn nun; cf. Delitzsch on Heb_12:1; (Ellicott on 1Th_4:8)), a particle introducing a conclusion with some special emphasis or formality, and generally occupying the first place in the sentence, wherefore then,for which reason, therefore, consequently: 1Th_4:8; Heb_12:1 (for ςΗμΞλΕΜο, Job_22:10; Job_24:22; 4Ma_1:34; 4Ma_6:28 variant; ; Sophocles, Xenophon, Plato, and following); cf. Klotz ad Devar. ii. 2, p. 738.
Mounce Concise Greek Dictionary
τοιγαροῦν toigaroun 2x
well then, so then, wherefore, for that reason, 1Th_4:8 ; Heb_12:1
Abbott-Smith Greek Lexicon
τοι -γαρ -οῦν ,
an inferential particle,
[in LXX : Job_22:10 ; Job_24:22 , Sir_41:16 , al. ;]
wherefore then, so therefore: 1Th_4:8 , Heb_12:1 (Hat., Plat ., al. ).†
Moulton & Milligan — Vocabulary of the Greek NT
τοιγαροῦν [page 637]
accordingly, wherefore ( 1Th_4:8 Heb_12:1 ) : P Tebt II. 315 .14 (ii/A.D.) τοιγαροῦν [μη ]δὲν ταραχ [θ ]ῇς , ἐγὼ γάρ [σ ]ε [ἀ ]παλλάξω , do not be disturbed on this account, as I will get you off (Edd.), P Giss I. 3 .7 (A.D. 117) (= Chrest . I. p. 571) χαίροντες τοιγαροῦν θύοντες τὰς ἑστίας ἀνάπτωμεν , and P Oxy I. 124 .7 (a schoolboy s exercise iii/A.D.) πέμψας τοιγαροῦν ὁ Ἄδραστος εἰς [Δε ]λφοὺς ἐπυνθάνετο τὴν αἰτίαν , Adrastus therefore sent to Delphi and inquired the cause (Edd.).
STEPBible — Tyndale Abridged Greek Lexicon
τοι-γαρ-οῦν
an inferential particle, [in LXX: Job.22:10 24:22, Sir.41:16, al. ;]
wherefore then, so therefore: 1Th.4:8, Heb.12:1 (Hat., Plat., al.).†
(AS)
📖 In-Depth Word Study
Consequently (5105) toigaroun
Consequently (5105) (toigaroun from toi = consequently, this particle strengthening a statement by assuring its reliability + gár = therefore + oun = then, therefore) is a particle which strongly or emphatically introduces an emphatic logical conclusion from the preceding facts. "For that very reason then". "For on this account therefore". This triple compound is draws a conclusion of emphasis.
Toigaroun is a strong Greek expression which could be translated something like
"Mark you, for this reason, therefore he who rejects..." - Paul proceeds to give another reason why believers should flee sexual immorality.
Toigaroun strongly introducing an inference from preceding facts. As as in the only other NT use in Hebrews 12:1 (note) toigaroun directs attention to the conclusion which follows in a more forcible way than do simpler and more frequent words.
As Richison observes...
A sex life governed by God’s call to holiness is the rationale for his next statements. The nature of the child of God stands in antithesis to the natural urges of the man without Christ.
He who rejects - Literally "the one who sets aside", "the rejecter".