3689 óntōs (the adverbial form of 1510 /eimí, "to be") – properly, exist; really be (exist, as reality). 3689 /óntōs ("substance as reality") is usually translated "indeed" and refers to what is genuinely important ("real").

STRONGS NT 3689: ὄντως

ὄντως (from ὄν; on adverbs formed from participles cf. Alexander Buttmann (1873) Ausf. Spr. § 115 a. Anm. 3; Kühner, § 335 Anm. 2), adverb, truly, in reality, in point of fact, as opposed to what is pretended, fictitious, false, conjectural: Mark 11:32 (see ἔχω, I. 1 f.); Luke 23:47; Luke 24:34; John 8:36; 1 Corinthians 14:25; Galatians 3:21 and Rec. in 2 Peter 2:18; ὁ, ἡ, τό ὄντως followed by a noun, that which is truly etc., that which is indeed (τά ὄντως ἀγατα ἤ καλά, P'lat. Phaedr., p. 260 a.; τήν ὄντως καί ἀληθῶς φιλίαν, Plato, Clit., p. 409 e.; οἱ ὄντως βασιλεῖς, Josephus, Antiquities 15, 3, 5): as ἡ ὄντως (Rec. αἰώνιος) ζωή, 1 Timothy 6:19; ἡ ὄντως χήρα, a widow that is a widow indeed, not improperly called a widow (as παρθένος ἡ λεγομένη χήρα, i. e., a virgin that has taken a vow of celibacy, in Ignatius ad Smyrn. 13 [ET] (cf. Lightfoot, in the place cited); cf. Baur, Die sogen. Pastoralbriefe, p. 46ff), 1 Timothy 5:3, 5, 16. (Euripides, Aristophanes, Xenophon, Plato, and following; the Sept. for אֻמְנָם, Numbers 22:37; for אָכֵן, Jeremiah 3:23; for אַך, Jeremiah 10:19.)



certainly, clean, indeed, verily.

Adverb of the oblique cases of on; really -- certainly, clean, indeed, of a truth, verily.

see GREEK on

ὠνόμασεν — 3 Occ.
ὠνομάσθη — 1 Occ.
ὀνομάζειν — 1 Occ.
ὀνομαζέσθω — 1 Occ.
ὀνομάζεται — 1 Occ.
ὀνομάζων — 1 Occ.
ὀνομαζόμενος — 1 Occ.
ὀνομαζομένου — 1 Occ.
ὄνον — 4 Occ.
ὄνου — 1 Occ.
ὄξος — 2 Occ.
ὄξους — 4 Occ.
ὀξεῖα — 2 Occ.
ὀξεῖαν — 1 Occ.
ὀξεῖς — 1 Occ.
ὀξύ — 4 Occ.
ὀπαῖς — 1 Occ.
ὀπῆς — 1 Occ.
ὄπισθεν — 7 Occ.
ὀπίσω — 35 Occ.