If you describe an army or sports team as invincible, you believe that they cannot be defeated.
unbeatable
You couldn't help feeling the military's fire power was invincible.
你不禁会感到这支军队的火力是无可匹敌的。
If someone has an invincible belief or attitude, it cannot be changed.
He also had an invincible faith in the medicinal virtues of garlic.
他对大蒜的药用功效深信不疑。