An Etymological Dictionary of Astronomy and Astrophysics

1. To bring to a fine or a pure state; free from impurities.
   

2. To make more fine, subtle, or precise (Dictionary.com).

Etymology (EN): → re-; → fine.

Etymology (PE): 1) Pâludan “to purify, starin, → filter.”

2. Nâzokidan, from nâzok “tender, delicate, subtle, neat,” → fine.