Strong's Greek Concordance

G5104: τοί

toí · “certainly”

Definition

an enclitic particle of asseveration by way of contrast; in sooth

KJV translates it as: (used only with other particles in the comparative, as G2544 (καίτοιγε), G3305 (μέντοι), G5105 (τοιγαροῦν), G5106 (τοίνυν), etc

Word origin: probably for the dative case of G3588 (ὁ);

Extended definition

1. enclit. Particle, serving to express belief in an assertion, let me tell you, surely, verily , used to express an inference, then, consequently , (Homer); and in [variant datesTragica Adespota, to introduce a general sentiment.
2. to strengthen other Particles, γάρ τοι, ἤτοι, καίτοι, μέντοι, τοιγάρτοι, etc.: compare τἆρα, τἄν, μεντἄν. (ML)

Abbott-Smith Manual Greek Lexicon (1922) via STEPBible TBESG (CC BY 4.0).

Words derived from G5104