IPA: /ˌoʊvərɪɡˈzjuːbərənt/
KK: /oʊvərɪgˈzubərənt/
Showing too much enthusiasm or excitement, often in a way that is excessive or overwhelming.
The overexuberant crowd cheered loudly for the team after their victory.
Overexuberant → It is formed from "over-" (meaning excessively) and "exuberant" (from Latin "exuberare", meaning to be abundant or overflowing). The word "overexuberant" means excessively enthusiastic or overflowing with excitement.
Think of being 'excessively' ('over-') 'abundant' or 'overflowing' with enthusiasm — that's what overexuberant means.