The Greek adjective amartyros (ἀμάρτυρος) means without witness or without testimony — composed of the alpha-privative and martys (witness). It appears once in Acts 14:17, where Paul asserts that God did not leave Himself without witness even among the Gentiles.
In his Lystra address, Paul argues that God's care of the nations — giving rain, fruitful seasons, and gladness — constituted a witness to Himself even before the gospel was proclaimed (Acts 14:17). General revelation means God is never truly without witness among any people. Creation, providence, and conscience all testify to God (Romans 1:20; 2:14–15). Yet the full witness is found only in Christ and the gospel (Acts 17:30–31).