The Defend move in Dungeon World is triggered when "you stand in defense of a person, item, or location" (emphasis mine). While our party was under attack by a gang of imps, our Cleric asked if he could defend two nearby members of the party. He read the move as being able to defend the location - being the room we were in, as being able to defend the party members in the room, where I read defending a location more like "Defend this doorway so no one can enter the room." I believe that part of the pressure of the move is choosing the one target to defend, but I fully admit that I could be interpreting this in an overly strict sense - so I would like to know whether or not a character taking the Defend move is able to defend multiple targets.
Somewhat related - but deals with Hack & Slash: Attacking multiple targets in DW