An Etymological Dictionary of Astronomy and Astrophysics

1. Fineness or elegance of feeling, taste, manners, language, etc.
   

2. The act or process of refining. the quality or state of being refined.
   

3. An improved, higher, or extreme form of something.
   Math.: A → set whose elements include the elements of a given set (Dictionary.com).

See also: Verbal noun of → refine.