| 1 | French | retardant | present participle of retarder |
| 2 | French | retarder | to retard, slow down; to postpone, put back |
| 3 | Latin | retardo | I hinder, delay, detain, impede or retard |
| 4 | Latin | rĕ- | — |
| 5 | Latin | prōdūcō | — |
| 6 | Latin | prō- | — |
| 7 | Proto-Italic | *pro- | — |
| 8 | Proto-Indo-European | pro- | toward, forward |
| 9 | Proto-Indo-European | por- | to give birth; forward, through; going, passage |
| 10 | Proto-Indo-European | per- | before, in front; first; to go through |
| 11 | Proto-Indo-European | pr̥tós | passed , crossed |