What is the meaning of -ity?

Used to form an uncountable noun from an adjective; especially, to form the noun referring to the state, property, or quality of conforming to the adjective's description.

Used to form a countable noun from an adjective, referring to someone or something that conforms to the adjective's description.

Used to form other nouns, especially abstract nouns.

Alternative form of -ety

forms masculine adjectives

Source: wiktionary.org