Unbeatable
Part of speech: adjective
Definition: That cannot be beaten, defeated or overcome
Example sentence: I was unbeatable - until I wasn't.
Invincible
Part of speech: noun
Definition: Someone or something that cannot be defeated, destroyed or killed.
Part of speech: adjective
Definition: Not possible to defeat, destroy or kill.
Example sentence: I'm not invincible. I am not picture-perfect. The reason I am here is not because of the money; if I get to entertain people and put a smile on their face, I feel content.