Related Clues:

• Knob on a branch
• Central portion
• Degree requirement, sometimes
• Bump on a log, e.g.
• Main meaning
• Need for a third degree?
• Worn-down end
• Crux of the matter
• Degree requirement, perhaps
• Main theme
• Grad student's project
• In the ___ of (among)
• Centering point
• Pencil stump, e.g.
• Wheel center