An Etymological Dictionary of Astronomy and Astrophysics

To change somewhat the form or qualities of; alter partially; amend.
To reduce or lessen in degree or extent; moderate; soften:

Etymology (EN): From O.Fr. modifier, from L. modificare “to impose a rule or pattern, regulate, restrain,” from modus “measure, rhythm, song, manner” PIE base *med-/*met- “to measure, limit, consider, advise, take appropriate measures”

• root of facere “to make”

Etymology (PE): Vâtarzidan, from vâ- prefix denoting “reversal, opposition; separation; repetition; open; off; away” (variant of bâz-, from Mid.Pers. abâz-, apâc-; O.Pers. apa- [pref.] “away, from;” Av. apa- [pref.] “away, from,”
apaš [adv.] “toward the back;” cf. Skt. ápāñc “situated behind”) + tarz “mode, manner” + -idan infinitive suffix.