ABD: In academic circles (for those of us who don't really travel there), it means "All But Dissertation."
In our household parlance, it also means "Heck yeah, baby! Luke defeneded his proposal sucessfully!! Now all he has to do is write the damn thing."
He commented that it seems silly for people to congratulate him on this step, since all he gets is the privilege of writing a 200+ page pager. But the milestones are important, and yesterday's defense marked an important point. So, happy happy joy joy!
Next steps? Job hunting and disseration. Oof.