rar·e·fied /ˈrærəˌfaɪd, ˈrɛr-/
  (a.)變成稀薄的,純化的,考究的
  Rar·e·fy v. t. [imp. & p. p. Rarefied p. pr. & vb. n. Rarefying ]  To make rare, thin, porous, or less dense; to expand or enlarge without adding any new portion of matter to; -- opposed to condense.
  rarefied
       adj 1: having low density; "rare gasses"; "lightheaded from the
              rarefied mountain air" [syn: rare, rarified]
       2: reserved for an elite group [syn: rarified]
       3: of high moral or intellectual value; elevated in nature or
          style; "an exalted ideal"; "argue in terms of high-flown
          ideals"- Oliver Franks; "a noble and lofty concept" [syn:
          exalted, high-flown, high-minded, lofty, rarified,
           idealistic, noble-minded]
  rarefy
       v 1: lessen the density or solidity of; "The bones are rarefied"
       2: make more subtle or refined [syn: sublimate, subtilize]
       3: weaken the consistency of (a chemical substance) [syn: attenuate]
       [also: rarefied]