Rar"e*fy (?), v. t. [imp. & p. p. Rarefied (?); p. pr. & vb. n. Rarefying (?).] [F. rar'efier; L. rarus rare + -ficare (in comp.) to make; cf. L. rarefacere. See -fy.]
To make rare, thin, porous, or less dense; to expand or enlarge without adding any new portion of matter to; -- opposed to condense.
© Webster 1913.
Rar"e*fy, v. i.
To become less dense; to become thin and porous.
"Earth
rarefies to dew."
Dryden.
© Webster 1913.