donut hole

noun5

1. •
   The empty space in the center of a donut.
2. •
   (US, Canada) A small, ball-shaped pastry, made in the same manner as a donut, roughly the size of the hole in a donut.

   • These donut holes are delicious!
3. •
   (US, slang) An income bracket in which an individual is ineligible for benefits, despite such benefits being available to those in both the immediately lower and higher income brackets.

   • Very few younger Americans have probably ever heard of the “donut hole” in Medicare's prescription drug program, but if you're on Medicare and need expensive drugs it's likely you have. — 2012
4. •
   (informal) A body of water in which no entity holds fishing rights, entirely enclosed by adjacent regions where such rights are legally allocated to various parties.
5. •
   (slang) The anus.