The figurative substance of a brain: mental ability, intelligence.
The substance of a brain, as a material or foodstuff.
The intelligent person or people in a group: the director, planner, administrator, etc.
Sanity.
Bits of rolled-up rubber shed by the tires of race cars that accumulate at the edges of the track, especially at the corners.
Any of several children's games played with small balls (made of marble or more commonly glass).