The quality or state of being fervid; intense, passionate feeling or expression demonstrated with great emotional depth.
From the adjective 'fervid' plus the English suffix '-ness', creating an abstract noun that expresses the quality of being fervid.
Fervidness is the noun form that sounds most natural in everyday modern English, though 'fervidity' and 'fervidness' mean nearly the same thing, showing English's love of multiple ways to express the same idea.
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