cavity

After confirming successful plant growth, the 'soil' was baked leaving only the glass with root cavities.

Colloid cysts typically form in a fluid-filled cavity in the centre of the brain, and are themselves filled with fluid, the Brains Trust says.

Researchers have explored how a particular chemical can selectively trap certain molecules in the cavities of its structure -- even though in normal conditions it has no such cavities.

By the early 1950s a consensus emerged that fluoride in very small amounts in drinking water could reduce cavities, especially in children, so putting fluoride in water systems began to spread.

This prolonged exposure increases the acidity of the mouth, erodes the teeth and causes cavities.