rarity
1. [ noun ] a rarified quality
Synonyms: low_density tenuity
Examples:

: "the tenuity of the upper atmosphere"

Related terms: density
2. [ noun ] noteworthy scarcity
Synonyms: infrequency rareness
Related terms: scarcity
3. [ noun ] something unusual -- perhaps worthy of collecting
Synonyms: curio oddment oddity peculiarity curiosity
Related terms: object whatchamacallit bric-a-brac collector's_item collectable