Of uncertain affinity; a witness (literally (judicially) or figuratively (genitive case)); by analogy, a "martyr" -- martyr, record, witness.
STRONGS NT 3144: μάρτυςμάρτυς (Aeolic μάρτυρ, a form not found in the N. T.; (etymologically one who is mindful, heeds; probably allied with Latinmemor, cf. Vanicek, p. 1201; Curtius, § 466)), μάρτυρός, accusative μάρτυρα, ὁ; plural μάρτυρες, dative plural μάρτυσι; the Sept. for עֵד; (Hesiod, Simonides, Theognis, others); a witness (one who avers, or can aver, what he himself has seen or heard or knows by any other means);
a. in a legal sense: Matthew 18:16; Matthew 26:65; Mark 14:63; Acts 6:13; Acts 7:58; 2 Corinthians 13:1; 1 Timothy 5:19; Hebrews 10:28.
b. in an historical sense: Acts 10:41; 1 Timothy 6:12; (2 Timothy 2:2); one who is a spectator of anything, e. g. of a contest, Hebrews 12:1; with a genitive of the object, Luke 24:48; Acts 1:22; Acts 2:32; Acts 3:15; Acts 5:32 G L T Tr WH; Acts 10:39; Acts 26:16; 1 Peter 5:1; with a genitive of the possessor 'one who testifies for one', Acts 1:8 L T Tr WH; c. in an ethical sense those are called μάρτυρες Ἰησοῦ, who after his example have proved the strength and genuineness of their faith in Christ by undergoing a violent death (cf B. D. American edition and Dict. of Chris. Antiq. under the word