As one of the Gentiles. By intercourse with them, relinquishment of Jewish observances, and adapting his teaching to their modes of thought. See Acts 17.
Under law (ἔννομος)
The expression differs from that in 1Co 9:20, ὑπὸ νόμον under law, though with only a shade of difference in meaning. Ἔννομος means subject to the law, but in the sense of keeping within (ἐν) the law.