Any person can claim to have a special relationship with God. Claims are easy to make. Therefore we may expect false leaders to make big claims about their special powers from God. In order to be more convincing they may use Bible words, but in ways that differ from the Bible itself. So it is important to begin with Scripture’s meanings for its own terms.
The Bible uses a number of terms for miracles. The words “wonder” and “sign” first appear when God sends Moses to Egypt. God reveals His plan to hit Egypt hard with “wonders”—which turn out to be the ten plagues.
So I will stretch out my hand and strike Egypt with all the wonders that I will do in it; after that he will let you go (Exodus 3:20 cf. 4:21).