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

(concentrat)

(ambitransitive) To bring to, or direct toward, a common center; to unite more closely; to gather into one body, mass, or force.

to concentrate rays of light into a focus

to concentrate the attention

Let me concentrate !

To increase the strength and diminish the bulk of, as of a liquid or an ore; to intensify, by getting rid of useless material; to condense (qualifier, as opposed to 'dilute').

to concentrate acid by evaporation

to concentrate by washing

To approach or meet in a common center; to consolidate.

Population tends to concentrate in cities.

* {{quote-book, year=2006, author=

, title=Internal Combustion , chapter=2 citation , passage=Buried within the Mediterranean littoral are some seventy to ninety million tons of slag from ancient smelting, about a third of it concentrated in Iberia. This ceaseless industrial fueling caused the deforestation of an estimated fifty to seventy million acres of woodlands.}}

To focus one's thought or attention (on).