1. A carrier of things for someone else; often used to refer to a carrier of illegal drugs, or a video game character who functions as a holding space for items for another character.
1. To hold or transit for someone else.
Mulebob is a 1st level character who's a mule for all our gear that we haven't sold yet.
We'll give that item to Mulebob to mule over to your character in that other place.