1. to execute or present an action, performance, or act without prior planning or preparation, in an impromptu manner
The jazz musicians performed spontaneously during the street festival.
Os músicos de jazz atuaram espontaneamente durante o festival de rua.
2. to do something naturally or instinctively without deliberate thought or direction
She performed spontaneously when asked to dance at the party.
Ela dançou espontaneamente quando pediriam para dançar na festa.