1. to respond to criticism, questions, or perceived threats by protecting oneself emotionally or psychologically, often with hostility or withdrawal
When confronted about his mistake, he reacted defensively instead of admitting the error.
Quando confrontado sobre seu erro, ele reagiu defensivamente em vez de admitir o problema.
2. to respond to an attack or threat by taking protective or aggressive action
The animal reacted defensively when approached by the stranger.
O animal reagiu defensivamente quando se aproximou o estranho.