In my studies I came across the term theonoms, meaning ruled by God. (from the Greek: theos + nomos). Does this term appear in the new testament or is it something that was developed later?
The term "theonomy" has sprung into popular use through the writings of "Christian Reconstructionists" (in particular: Gary North, Greg Bahnsen, and R.J. Rushdoony). According to Wikipedia, the oldest recorded use of the term by an English author is from Paul Tillich (who, incidentally, meant by it something quite different from what the reconstructionists usually mean).
In terms of the Greek New Testament, the closest thing that I could find is in Romans 7:22, 7:25, and 8:7. In particular, Romans 7:25 contains "νόμῳ Θεοῦ" in the majority text, although I'm not sure whether this passage would be understood by the reconstructionists as referring to their concept of theonomy or not.