v. To expand or enlarge without adding any new portion of matter to.
the GNU version of the Collaborative International Dictionary of English
v. To make rare, thin, porous, or less dense; to expand or enlarge without adding any new portion of matter to; -- opposed to condense.
verb-intransitive. To become less dense; to become thin and porous.
The Century Dictionary and Cyclopedia
To make rare, thin, porous, or less dense; expand or enlarge without adding any new matter; figuratively, to spread or stretch out; distend: opposed to condense.
To become rare; pass into a thinner or less dense condition.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
v. lessen the density or solidity of
v. weaken the consistency of (a chemical substance)
v. make more subtle or refined
Word Usage
"I'm no stranger to the Gentri-verse and I ride my bike all the time, and I can't even relate to him--which, I guess, is why I also can't always relate to the "bike culture," since they seem so determined to rarefy the normal."