What does cavity mean?
A cavity is a hollow space or opening within what would otherwise be a solid structure. The word appears across several domains: in dentistry, a cavity refers to a hole caused by tooth decay, making it one of the most familiar medical terms in everyday language; in anatomy and biology, it denotes a natural chamber within the body, such as the nasal cavity or abdominal cavity; and in engineering or materials science, it describes an empty space trapped inside a solid object. Cavities carry a mildly negative connotation when linked to decay or damage, but are neutral when describing normal anatomical structures. Derived from the Latin 'cavus', meaning hollow, the word shares roots with 'concave' and 'cavern'. Its precision and broad applicability make it essential vocabulary in both clinical settings and general descriptions of form and structure.
nounA hollow space or hole within a solid body or object, such as a decayed area in a tooth or an empty chamber in the body.
- A decayed area of a tooth where enamel has eroded and formed a hole (dental sense).
- Any hollow space within a solid body, organ, or object (e.g. nasal cavity, oral cavity).
- An empty gap or void within a manufactured or structural material.
"The dentist found a small cavity forming between two of her molars."
"Brushing twice daily helps prevent cavities from forming in the molars."
"Surgeons drained fluid that had accumulated in the pleural cavity around his lung."
Standard plural; used freely for multiple instances of tooth decay or anatomical spaces.
"Poor oral hygiene can lead to multiple cavities over time."
The word 'cavity' comes from Latin 'cavus' meaning 'hollow' — the same root that gives us 'concave', so every time you hear about a cavity, you're literally hearing about something hollowed out.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of cavity
Cavity derives from the Late Latin 'cavitas', meaning hollowness, which itself stems from the Latin adjective 'cavus', meaning hollow. It entered English in the early modern period, likely via French 'cavité'. Cognates and related words sharing this root include 'concave', 'cavern', and 'cave', all pointing to the underlying idea of a hollowed-out space.
Related word forms
How cavity is actually used
Mostly used in medical, dental, scientific, and technical contexts; in everyday speech it most commonly refers to tooth decay. In American English 'having a cavity' almost always means tooth decay, whereas in British English people more often say 'filling' or 'hole in a tooth'.
Easily confused with cavity
A cavern is a large natural underground cave, whereas a cavity is any hollow space within a body or object and is often much smaller.