'Course' in the Bible

it seemed good to me also, having traced the course of all things accurately from the first, to write unto thee in order, most excellent Theophilus;

There was in the days of Herod, king of Judaea, a certain priest named Zacharias, of the course of Abijah: and he had a wife of the daughters of Aaron, and her name was Elisabeth.

Now it came to pass, while he executed the priest's office before God in the order of his course,