| 1 | English | enforce | To keep up, impose or bring into effect... |
| 2 | Middle English | enforcen | — |
| 3 | Old French | enforcier | to fortify; to strengthen; to strengthen; to... |
| 4 | Franco-Provençal | forciér | to force |
| 5 | Latin | fortio | I force |
| 6 | Late Latin | fortia | nominative neuter plural of fortis; accusative... |
| 7 | Latin | fortis | strong, powerful; firm, resolute, steadfast,... |
| 8 | Old Latin | forctis | strong |
| 9 | Proto-Italic | forktis | strong, robust |
| 10 | Proto-Indo-European | bʰerǵʰ- | to rise; high, lofty; hill, mountain |