Probably from the base of G3735; right (as {rising}) that {is} (perpendicularly) erect (figuratively {honest}) or (horizontally) level or direct: - {straight} upright.
Verse
Matrix
Gal 2:14But when I saw that they walkedG3716 not uprightlyG3716 according to the truth of the gospel, I said unto Peter before them all, If thou, being a Jew, livest after the manner of Gentiles, and not as do the Jews, why compellest thou the Gentiles to live as do the Jews?