Rareness; a rare thing.
- Nuttall's Standard dictionary of the English language. By Nuttall, P.Austin. Published 1914. (noun) (n.) (noun)
The state or quality of being infrequent or uncommon; a choice or scarce article; unusual excellence; thinness; as, the rarity of the air at a height.
- The Winston Simplified Dictionary. By William Dodge Lewis, Edgar Arthur Singer. Published 1919. (noun) (n.) (noun)
State of being uncommon; value arising from scarcity; thinness; opposed to density; rare bit, a dainty morsel.
- Etymological and pronouncing dictionary of the English language. By Stormonth, James, Phelp, P. H. Published 1874. (noun) (n.) (noun)
State of being rare: thinness: subtilty: something valued for its scarcity: uncommonness.
- The american dictionary of the english language. By Daniel Lyons. Published 1899. (noun) (n.) (noun)
State of being rare; something uncommon.
- The Clarendon dictionary. By William Hand Browne, Samuel Stehman Haldeman. Published 1894. (noun) (n.) (noun)

Usage examples:

Our dip was refreshing; we could only find time for it on Sundays and holidays such as this, and probably we appreciated it all the more for its rarity
- The Moving Finger A Trotting Christmas Eve at Warwingie Lost! The Loss of the "Vanity" Dick Stanesby's Hutkeeper The Yanyilla Steeplechase A Digger's Christmas by Mary Gaunt
It had been used in France for jewelry and knicknacks, and a rattle of it had been presented to the baby son of the Emperor of France as a great rarity
- Diggers in the Earth by Eva March Tappan
Its modern rarity may, however, only make it the more precious in a book, and it is certainly not the least important element in the popularity of Boswell's work.
- Dr. Johnson and His Circle by John Bailey