refine

verb

1. (transitive)To purify; reduce to a fine, unmixed, or pure state; to free from impurities.

   “to refine gold”

   “to refine iron”

   “to refine wine”

   “to refine sugar”

   “The dawn of the oil age was fairly recent. Although the stuff was used to waterproof boats in the Middle East 6,000 years ago, extracting it in earnest began only in 1859 after an oil strike in Pennsylvania.[…]It was used to make kerosene, the main fuel for artificial lighting after overfishing led to a shortage of whale blubber. Other liquids produced in the refining process, too unstable or smoky for lamplight, were burned or dumped.”

2. (intransitive)To become pure; to be cleared of impure matter.
3. (transitive)To purify of coarseness, vulgarity, inelegance, etc.; to polish.

   “to refine someone's manners”

   “to refine a language”

   “a refined style”

   “to refine one's tastes”

4. (ambitransitive)To improve in accuracy, delicacy, or excellence.

   “My dear Harriet, you must not refine too much upon this charade.—You will betray your feelings improperly, if you are too conscious and too quick, and appear to affix more meaning, or even quite all the meaning which may be affixed to it.”

   “Adjust the volume, tweak the contours, refine the timing and, if need be, fiddle with the setting, and the hoariest yuck-fest can seem as dewy as a morning in May. Examples of tales told ticklingly are in unusual abundance here, with comedies for every taste within the mainstream of London theater.”

   “HS2 Ltd has continued to refine the designs, so that seven fewer ancient woodlands will be affected. This reduces the total number to 25. And of those 25 woodlands, 85% of the total area will remain untouched by HS2.”

5. (transitive)To make nice or subtle.

   “to refine thought”

   “to refine someone's language”