Cavity/ˈkævəti/ Definition 1 of 4Pro Tip 1/3Metaphorical Use Sometimes 'cavity' is used metaphorically to express emptiness in non-physical things. The book left a cavity in her heart. Pro Tip 2/3Negative Connotation 'Cavity' often implies a problem or a deficiency needing to be addressed. The engineers found a cavity in the spacecraft's insulation. Pro Tip 3/3Physical Structures In construction or architecture, 'cavity' refers to a designed gap within walls. This building has cavity walls for better insulation.