Emily Dickinson Lexicon

RAR-E-FAC'TION, n. [Fr. See Rarefy.]

The act or process of expanding or distending bodies, by separating the parts and rendering the bodies more nice or porous, by which operation they appear under a larger bulk, or require more room, without an accession of new matter; opposed to condensation; as, the rarefaction of air. – Encyc.