1. to engage in combat or struggle against an opponent, enemy, or opposing force
The soldiers fought against the invading army.
Os soldados lutaram contra o exército invasor.
2. to oppose or resist something actively; to work to prevent or overcome something negative
We must fight against corruption in government.
Devemos lutar contra a corrupção no governo.
3. to make efforts to overcome a difficulty or challenge
She is fighting against her fear of heights.
Ela está lutando contra seu medo de alturas.