| 1 | Old High German | rīhhi | rich, mighty; power, might, empire; realm |
| 2 | Proto-West Germanic | rīkī | mighty, powerful; rich; kingdom, realm |
| 3 | Proto-Germanic | rīkijaz | kingly, royal, noble; mighty, powerful; rich |
| 4 | Proto-Germanic | rīks | king, ruler |
| 5 | Proto-Celtic | rīxs | king |
| 6 | Proto-Indo-European | h₃rḗǵs | king, ruler |
| 7 | Proto-Indo-European | h₃reǵ- | to straighten, to right oneself; right; just |