A
deadline that is expected to or has already moved. Proper deadlines are immovable because they're "dead"; movement betrays non-deadness, and because
deadness is the defining feature of a proper
deadline, its absence renders the line dud.
Greg: Right, I'm
going down the pub.
Brad: But you haven't finished your coursework essay yet and the deadline's tomorrow morning!
Greg: Chill dude, that's actually a dudline.
Brad:
You don't know that!
Greg: Sure I do. Just look at what happened the last two times.
Brad: Hmm, yeah, I suppose
you're right.