What is an archangel?

An archangel is a chief angel or the prince of the angels. The word "archangel" can be found twice in the Scriptures. The archangel Michael is also called a "prince" in the book of Daniel.

"For the Lord himself shall descend from heaven with a shout, with the voice of the archangel, and with the trump of God: and the dead in Christ shall rise first" (1 Thessalonians 4:16). 

"Yet Michael the archangel, in contending with the devil, when he disputed about the body of Moses, dared not bring against him a reviling accusation, but said, "The Lord rebuke you!" (Jude 1:9). 

"But I will tell you what is noted in the Scripture of Truth. (No one upholds me against these, except Michael your prince" (Daniel 10:21).

"At that time Michael shall stand up, The great prince who stands watch over the sons of your people; and there shall be a time of trouble, Such as never was since there was a nation, Even to that time. And at that time your people shall be delivered, every one who is found written in the book" (Daniel 12:1).