From Hull AWE
Cave can cause problems for readers unfamiliar with some of the possible ambiguities.
- The usual meaning of 'cave' (pronounced to rhyme with 'save' and brave' (IPA: /keɪv/) in English) is a 'an open space formed, naturally, underground'. These may be made by waves, on rocky coasts; water erosion in any rocks; dissolving of material in soluble rocks like limestone; caves in lava formed by shrinkage while cooling; melting in glaciers; etc. The word can also be used figuratively to describe certain man-made structures that resemble natural caves.
- The French word cave looks exactly the same, and comes from the same root; but is used for a cellar - usually artificial rather than natural. It is pronounced like 'carve' (IPA: /kɑːv/).
- Etymological note: this sense of the word cave derives from the Latin adjective cavus, 'hollow'. From this root we also get the nouns cavern (a stylish or poetic word meaning 'a large cave'), and cavity, a hollow space in a solid object, such as teeth (in building, a cavity wall is one with two vertical structures enclosing a hollow space which may be used for insulation); the adjectives concave, describing a curve which is like the inside of a circle or sphere, the opposite of convex (spectacle lenses for short sight are concave; for long sight convex), and cavernous, meaning 'hollow', and usually implying size (a man may yawn cavernously); and the verb excavate, meaning 'to hollow out', and more commonly 'to dig up' (much archaeological research is carried out in excavations). Engineers are aware of the phenomenon of cavitation in which bubbles ('cavities') form and collapse in fluids as a result of changes in pressure, which may result in damage to structures such as propellers and pumps, but may also be harnessed usefully in chemical engineering processes
- In rather dated schoolboy slang (at schools like public schools and grammar schools, at which Latin was intensively studied), the homograph cave (italicized because it is a Latin word) was used as a warning. It is derived from the verb cavēre 'to beware' (like caveat), and means 'Look out!' (usually of the approach of a teacher, or other person in authority). A boy deputed to act as look-out was said to be 'keeping cave'. The word was pronounced in different ways: to rhyme with 'wavy' and 'navy' (IPA: /keɪv ɪ or iː/); (by those who listened to their teachers) to rhyme with 'carve A' (IPA: /kɑːv e/); and for those who cared not a bit for tradition like the more usual word (IPA: /keɪv/).
- Cave canem is the Latin for 'Beware of the Dog'. Such a sign, in mosaic, is to be seen in the 'house of the Tragic Poet' in the Roman town of Pompeii, destroyed in a volcanic eruption in 79 CE.