rarefy

verbs

lessen the density or solidity of
"The bones are rarefied"
rarefy
is derived from
rarefaction
is a type of (narrower)
cause to change; make different; cause a transformation
"The advent of the automobile may have altered the growth pattern of the city"; "The discussion has changed my thinking about the issue"
alter, change, modify
make more subtle or refined
rarefy, sublimate, subtilize
weaken the consistency of (a chemical substance)
attenuate, rarefy
is derived from
rarefaction