Wiktionary
n. (context idiomatic English) A person who participates in entertainment events in a very enthusiastic manner and who has a leading role in inspire others to join in the spirit of festivity.
Usage examples of "life and soul of the party".
All I was going to say was some of us are a bit worried that he never comes down to the pub any more on account of the fact that he used to be the life and soul of the party, but thanks for that.
After having been the life and soul of the party for a few glorious weeks, it was extremely annoying to be suddenly relegated to the sidelines.
Your father and mother were the life and soul of the party, in venting amusements, or narrating a touching story in the evenings, so as to beguile the weary time.
Rochester and -- because closely connected with him -- Miss Ingram were the life and soul of the party.