What part of speech is uninterestingness?

Uninterestingness can be categorized as a noun.

Parts of speech

• 1. uninterestingness is a noun, singular of uninterestingnesses.

Inflections

Noun

• Singular

  Plural
• uninterestingness 

  uninterestingnesses 

• Singular: uninterestingness 
• Plural: uninterestingnesses 

What does uninterestingness mean?