Verb

(refin)

To reduce to a fine, unmixed, or pure state; to free from impurities; to free from dross or alloy; to separate from extraneous matter; to purify

* {{quote-magazine, date=2013-08-03, volume=408, issue=8847, magazine=(The Economist)

, title= Yesterday’s fuel , passage=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.

To purify from what is gross, coarse, vulgar, inelegant, low, and the like; to make elegant or excellent; to polish.

To become pure; to be cleared of feculent matter.

To improve in accuracy, delicacy, or excellence.

To affect nicety or subtlety in thought or language.

Verb

To make high; to raise higher; to elevate.

To advance, increase, augment, make larger, more intense, stronger etc.

:to heighten beauty

:to heighten a flavor or a tint.

* 2006 , Ashley Seager, Employment rise gives chancellor a boost'', published in ''The Guardian Online , 6 December 2006

*:If Mr Brown chooses, he could raise his estimate of the economy's "trend" rate of growth in the coming years and so heighten his hopes of tax revenues.