cavˈitate intransitive verb

To form hollows

cavitāˈtion noun

1. The formation of cavities in a structure, or of gas bubbles in a liquid, or of a vacuum, or of a partial vacuum as between a body moving in a fluid and the fluid
2. A cavity

cavˈitied adjective

cavity radiation noun (physics)

The radiation emerging from a small hole leading from a constant temperature enclosure

cavity wall noun

A wall consisting of two layers with an air-space between (this space often later filled in with insulating material to provide energy-conserving cavity-wallˈ insulation