Boisterous is a word used to describe someone spirited, loud, and slightly out of control — like someone with a spring in their step and a song in their heart singing to strangers on the street.
Boisterous means "loud, clamorous, and unrestrained." Think of children on a playground or a popular restaurant or a litter of puppies as boisterous. This word, which comes from Middle English, can also refer to very intense storms. You could call a hurricane boisterous, but you will most likely hear this word used to describe people.