Definitions for "Rarefy"
Keywords:  porous, dense, thin, condense, enlarge
To make rare, thin, porous, or less dense; to expand or enlarge without adding any new portion of matter to; -- opposed to condense.
To become less dense; to become thin and porous.
Keywords:  lessen, density, solidity, bones
lessen the density or solidity of; "The bones are rarefied"
Keywords:  subtle, refined
make more subtle or refined
weaken the consistency of (a chemical substance)