4. Characterised by wide separation of parts; of loose texture; not thick or dense; thin; as, a rare atmosphere at high elevations. Water is nineteen times lighter, and by consequence nineteen times rarer, than gold. (Sir I. Newton)
Synonym: Scarce, infrequent, unusual, uncommon, singular, extraordinary, incomparable.
Rare, Scarce. We call a thing rare when but few examples, specimens, or instances of it are ever to be met with; as, a rare plant. We speak of a thing as scarce, which, though usually abundant, is for the time being to be had only in diminished quantities; as, a bad harvest makes corn scarce. A perfect union of wit and judgment is one of the rarest things in the world. (Burke) When any particular piece of money grew very scarce, it was often recoined by a succeeding emperor. (Addison)
Origin: F, fr. L. Rarus thin, rare.