'Mighty' in the Bible

And when the sabbath was come, he began to teach in the synagogue: and many hearing him were astonished, saying, Whence hath this man these things? and, What is the wisdom that is given unto this man, and what mean'such mighty works wrought by his hands?

And he could there do no mighty work, save that he laid his hands upon a few sick folk, and healed them.

But Jesus said, Forbid him not: for there is no man who shall do a mighty work in my name, and be able quickly to speak evil of me.