To reduce to a pure state; purify, To use precise distinctions and subtlety in thought or speech, To improve in accuracy, delicacy, or excellence, transitive verb_ 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; to defecate, To purify from what is gross, coarse, vulgar, inelegant, low, and the like; to make elegant or exellent; to polish, verb_ 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; as, to refine gold or silver; to refine iron; to refine wine or sugar, To become pure; to be cleared of feculent matter, To affect nicety or subtlety in thought or language

Simple past tense and past participle of clear,

The act or process of clearing, A space cleared; a clearing, The act of clearing or something (such as a space) cleared