If you're looking for a noun to describe someone or something full of enthusiasm and excitement, you could use:
* Ebullience: This is the noun form of the adjective "ebullient."
* Exuberance: This noun means a lively and enthusiastic expression of happiness or excitement.
* Vivacity: This noun refers to the quality of being lively and animated.
* Spirit: This noun can refer to a person's general attitude or mood, and can be used to describe someone with a lively and positive spirit.
For example, you could say:
* "Her ebullience was contagious, and soon everyone was laughing and joking."
* "The children's exuberance was a joy to watch."
* "The party was full of vivacity and laughter."
* "He had a spirit that was impossible to dampen."