| 1 | New Latin | rectum | accusative supine of regō; nominative neuter... |
| 2 | Latin | rectum | accusative supine of regō; nominative neuter... |
| 3 | Latin | rectus | ruled, having been ruled, governed, having been... |
| 4 | Latin | regere | second-person singular future passive indicative... |
| 5 | Latin | rego | I rule, govern; I guide, steer; I oversee, manage |
| 6 | Proto-Italic | regō | — |
| 7 | Proto-Indo-European | h₃réǵeti | to be straightening, to be setting upright |
| 8 | Proto-Indo-European | h₃reǵ- | to straighten, to right oneself; right; just |