/rair"i tee/ , n. , pl. rarities .
1. something rare, unusual, or uncommon: Snowstorms are a rarity in the South.
2. something esteemed or interesting in being rare, uncommon, or curious: That folio is a rarity that will bring a good price.
3. the state or quality of being rare.
4. rare occurrence; infrequency: Volcanic eruptions on the island occur with great rarity.
5. unusual excellence.
6. thinness, as of air or a gas.
[ 1550-60; raritas thinness, equiv. to rar ( us ) RARE 1 + -itas -ITY ]