Excitability
/ɪkˌsaɪtəˈbɪləti/
Definition 1 of 2
Pro Tip 1/3Emotional Aspect
Refers to someone's tendency to react with strong emotions, often quickly. 
Her excitability made the surprise party an overwhelming experience.
Pro Tip 2/3Potential Negativity
Sometimes implies a lack of control or professionalism; may be seen negatively in formal situations. 
His excitability during meetings was perceived as unprofessional by his colleagues.
Pro Tip 3/3Intensity Variance
This trait can vary greatly among individuals; some may show mild excitability, while others, extreme. 
Unlike her brother's mild interest, Lucy's high excitability at the theme park was infectious.