A word that means "first gospel." It is a combination of two Greek words: protos (meaning "first") and evangelion (meaning "gospel" or "good news").
It refers to the first message of redemption God spoke after the fall of man (when humans first sinned). Speaking to Satan (embodied in a serpent), God said, "And I will put enmity between you and the woman, and between your seed and her seed. He will crush your head, and you will strike his heel" (Genesis 3:15).
In this protevangelium (or first gospel), we have the first revelation of both the humanity (her offspring) and the divinity (crushing the head of the serpent) of the great Deliverer. God promises a Deliverer who will destroy Satan but will suffer in the process. This refers to Jesus's death on the cross. In suffering that death, Jesus defeated the devil who had the power of death (Hebrews 2:14).