1. to conduct oneself in a polite, respectful, and socially acceptable manner
The children were asked to be well-behaved during the ceremony.
Pediram às crianças que se comportassem bem durante a cerimônia.
2. to act in accordance with rules or expectations; to follow proper etiquette
She knew she had to be well-behaved at her grandmother's house.
Ela sabia que tinha que se comportar bem na casa da avó.