IPA: /ˈɡliːfəl.nəs/
KK: /ˈɡliːfəl.nəs/
The state of being very happy and full of joy.
Her gleefulness was evident as she danced around the room.
Gleefulness → It is formed from "gleeful" (from Old English "gleo", meaning joy or mirth) and "-ness" (meaning the state or quality of). The word "gleefulness" refers to the state of being full of joy or mirth.
Think of 'glee' as joy and '-ness' as the state of being, so 'gleefulness' means the state of being joyful.