Lexical Definition

‎ὄντως‎ óntōs (on'-toce) really G:ADV
adverb of the oblique cases of ‎ὤν‎

certainly, clean, indeed, of a truth, verily.

Usage: 2 forms in 13 verses
Form Translated As     In Verse(s)
ὄντωσ Certainly Luke.23.471Cor.14.25
Indeed Luke.24.34John.8.36Gal.3.211Tim.5.5
truly Mark.11.321Tim.5.31Tim.5.161Tim.6.19
όντωσ Really LXX.Num.22.37LXX.Jer.3.23LXX.Jer.10.19

Abbott-Smith

ὄντως, adv. (< ὤν, ptcp. of εἰμί, sum), [in LXX: Nu 22:37 (אֻמְנָם), Je 3:23 (אָכֵן), 10:19 (אַךְ), III Ki 12:24, Wi 17:14*;]
really, actually, truly: Mk 11:32, Lk 23:47 24:34, Jo 8:36, I Co 14:25, Ga 3:21; ἡ ὄ. ζωή, I Ti 6:19; ἡ ὄ. χήρα, I Ti 5:3, 5, 16.†

Abbott-Smith References

Book Refs
Numbers 22:37
1 Kings 12:24
Jeremiah 3:23 · 10:19
Mark 11:32
Luke 23:47 · 24:34
John 8:36
1 Corinthians 14:25
Galatians 3:21
1 Timothy 5:3 · 5:5 · 5:16 · 6:19

Liddell-Scott-Jones

ὄντως,

adverb participle of εἰμί (sum), really, actually, verily, with Verbs, [Refs 5th c.BC+]; ὄντως τε καὶ ἀληθῶς really and truly, [Refs 5th c.BC+]; opposed to to ὡς ἔπος εἰπεῖν, [Refs 5th c.BC+]; to εἰκότως, [Refs 5th c.BC+]participle ὤν, οὖσα, ὄν, to imply real existence, [Refs]: also with Nouns, τὰ ὄντως ἀγαθά [ὄντως φιλομαθής [prev. author] “R.” 490a; ὄντως ἑταίρας 4th c.BC: Antiphanes Comicus 212.6, compare 4th-3rd c.BC: Menander Comicus 367, etc.: not used by 5th c.BC: Thucydides Historicus or 4th c.BC: Aristoteles Philosophus, nor in \_Ionic dialect\_ (ἐόντως is not found) ">Refs 5th c.BC+]; more freq in the later dialogues of [Refs 5th c.BC+]