1. to respond to something in a spontaneous, unforced, or instinctive manner without deliberate thought or artifice
When she heard the good news, she reacted naturally with excitement and joy.
Quando ouviu as boas notícias, ela reagiu naturalmente com entusiasmo e alegria.
2. to behave authentically and genuinely in response to a stimulus or situation
The actor was instructed to react naturally to his co-star's improvisation.
O ator foi instruído a reagir naturalmente à improvisação de seu colega.