What is the meaning of rarefied?

verb

• Lessen the density or solidity of.
  • usage: "The bones are rarefied"
  • synonyms: rarefy
• Make more subtle or refined.
  • synonyms: rarefy, sublimate, subtilize
• Weaken the consistency of (a chemical substance.
  • synonyms: rarefy, attenuate

adjective

• Having low density.
  • usage: "rare gasses"; "lightheaded from the rarefied mountain air"
  • synonyms: rare, rarified
• Of high moral or intellectual value; elevated in nature or style.
  • usage: "an exalted ideal"; "argue in terms of high-flown ideals- Oliver Franks; "a noble and lofty concept"; "a grand purpose"
  • synonyms: exalted, elevated, sublime, grand, high-flown, high-minded, lofty, rarified, idealistic, noble-minded