What is the meaning of Rarity?

A measure of the scarcity of an object.

Thinness; the property of having low density

A rare object.

Jespersen, Otto (1909) A Modern English Grammar on Historical Principles (Sammlung germanischer Elementar- und Handbücher; 9), volumes I: Sounds and Spellings, London: George Allen & Unwin, published 1961, § 4.71, page 140.

rarity”, in OneLook Dictionary Search.

Source: wiktionary.org