Lexical Definition

‎μαρτύρομαι‎ martýromai (mar-too'-rom-ahee) to testify G:V
middle voice from ‎μάρτυς‎

take to record, testify.

Usage: 3 forms in 5 verses
Form Translated As     In Verse(s)
μαρτύρομαι I testify Acts.20.26Gal.5.3Eph.4.17
μαρτυρόμενοσ bearing witness Acts.26.22
μαρτυρόμενοι charging 1Thess.2.12

Abbott-Smith

** μαρτύρομαι (< μάρτυρ), [in LXX: Jth 7:28, I Mac 2:56 א)*;]
to summon as witness (M, Th., 25 f.; Hort., 1Pe., 53 f.; Lft., Notes, 29; Ga 203), hence,
(a) to protest, affirm solemnly: seq. ὅτι, Ac 20:26, Ga 5:3;
(b) to adjure, beseech: c. dat. pers., Ac 26:22; c. acc. et inf., Eph 4:17; seq. εἰς, I Th 2:12 (cf. δια-, προ-μαρτύρομαι).†

Abbott-Smith References

Book Refs
Acts 20:26 · 26:22
Galatians 5:3
Ephesians 4:17
1 Thessalonians 2:12

Liddell-Scott-Jones

μαρτύρομαι [],

future μαρτῠροῦμαι (δια-) [LXX+2nd c.AD+]: aorist ἐμαρτῡράμην [Refs 5th c.BC+]:—call to witness, invoke, with accusative person, [Refs 5th c.BC+]; especially of the gods, Ἄρτεμιν, γαῖαν καὶ θεούς, [Refs 5th c.BC+]; δαίμονας, ὡς.. [Refs]: with accusative et infinitive, ὑμᾶς δ᾽ ἀκούειν ταῦτ᾽ ἐγὼ μαρτύρομαι [Refs 4th c.BC+]participle, μαρτύρομαι τυπτόμενος I call you to witness that.., [Refs 5th c.BC+]

__2 with accusative of things, call one to witness a thing, [Refs 5th c.BC+]
__3 protest, asseverate, μ. ὅτι.. [μαρτύρομαι">Refs 5th c.BC+] I protest, [Refs 5th c.BC+]
__4 with accusative person et genitive of things, οἱ δὲ τῆς τῶν θεῶν.. παραγωγῆς τὸν Ὅμηρον μ. ὅτι.. cite Homer as a witness of.., [Refs 5th c.BC+] [same place]; μ. τινὶ ὅτι.. [NT]; τοὺς ἀποστάντας μ. τῆς ἐπιορκίας remind them of.., [Refs 2nd c.AD+]

LSJ Scripture Refs: LXX.Ps.80.9*Gal.5.3