This is a subsidiary post of The Study of Canon and the Etymology of Certain Terms.
More information on sources referenced in this post can be found in Annotated Bibliography on New Testament Text and Canon.
The term “gospel” was originally a theological term referring to the message of salvation; later (mid-2nd Century) became a literary term with a reluctance to speak of multiple gospels. Gamble TNTC p 30, 35.
See Gamble in The Canon Debate, loc 6013
But is “gospel” in Mark 1:1 being used to describe a writing?