IPA: /ˈhjuːmərəsnəs/
KK: /ˈhjuːmərəsnəs/
The quality or state of being funny or amusing.
Her humorousness made the meeting much more enjoyable.
Humorousness is formed from "humor" (from Latin "humor", meaning fluid or moisture, which evolved to mean a mood or temperament) and the suffix "-ous" (meaning full of) and "-ness" (meaning the state of). The word refers to the state of being full of humor or possessing a humorous quality.
Think of 'humor' as a mood or temperament, and remember that 'humorousness' means the state of being full of humor.