Invincible means impossible to defeat or overcome. When someone or something is invincible, no opponent can beat them, no obstacle can stop them, and no challenge can break their strength.

In stories and myths, invincible warriors like Achilles seemed unbeatable in battle. Superman appears invincible because bullets bounce off him and nothing can hurt him. A chess champion on a long winning streak might seem invincible to other players.

But invincible doesn't always mean literally unbeatable. Sometimes people feel invincible when they're full of confidence and energy, like after winning a championship or mastering a difficult skill. A team that has won ten games in a row might start feeling invincible, even though they could still lose the next game.

Notice that truly invincible things are rare: even the strongest castles eventually fall, even the best athletes eventually lose, and even the mightiest empires eventually crumble. When someone seems invincible, it usually means they haven't met their match yet. The opposite of invincible is vulnerable, meaning able to be harmed or defeated.