# virtual

Pronunciation: say "VUR-choo-uhl" US /ˈvɜɹt͡ʃuəl/, UK /ˈvɜːt͡ʃʊəl/

## Adjective

1. Existing in effect or essence rather than in actual fact; imitated or simulated.
   - Simple: Being something in effect or result, but not in real fact.
   - _With the president abroad, the vice president became the virtual leader of the cabinet._
   - _The treaty created a virtual alliance, even though no formal pact was ever signed._
2. Amounting to something for practical purposes though not technically; almost complete or very near.
   - Simple: Almost complete or nearly total, even if not quite exact.
   - _The factory closure caused a virtual collapse of the town's economy._
   - _His silence on the matter amounted to a virtual admission of guilt._
3. Operating through a computer or online rather than being physically present.
   - Simple: Done through a computer or the internet instead of in person.
   - _Most of the conference shifted to a virtual format last year._
   - _The clinic now offers virtual appointments for routine checkups._
4. Simulated within a computer or online rather than existing as a physical thing.
   - Simple: Made by a computer to seem real, but not actually real.
   - _Architects walked clients through a virtual model of the unbuilt tower._
   - _The headset drops you into a fully virtual landscape._
6. Of a class member in programming: able to be overridden by a different implementation in a subclass.
   - Simple: In programming, able to be replaced by a new version in a related class.
   - _Declaring the method virtual lets each subclass define its own behavior._
   - _A virtual function in the base class is overridden by the derived one._
8. In optics, of a focus, point, or image, from which light only appears to come, rather than actually meeting there.
   - Simple: In optics, describing an image or point that light only seems to come from.
   - _A concave lens produces a virtual image that appears smaller and upright._
   - _Because the rays only seem to meet there, the focus is virtual rather than real._
9. In physics, describing particles that exist only briefly, their fleeting existence allowed by the Heisenberg uncertainty principle.
   - Simple: In physics, describing tiny particles that exist for only a very short time.
   - _Two electrons repel each other by exchanging virtual photons._
   - _A virtual particle borrows energy for a tiny fraction of a second before disappearing._
10. Describing a quantum state that is intermediate, exists only briefly, and cannot be observed directly.
   - Simple: Describing a tiny state in physics that lasts only a moment and cannot be seen directly.
   - _A virtual photon mediates the electromagnetic force without ever being directly detected._
   - _These calculations treat the virtual states as intermediate steps that vanish almost as soon as they form._
12. Describing an effect something would produce if counteracting factors like friction were ignored; especially, of a head of water, the pressure it would give absent friction.
   - Simple: Describing an effect something would have in theory if things like friction were ignored.
   - _The virtual head of water represents the pressure available before friction in the pipe reduces it._
   - _Hydraulic engineers compare the virtual pressure with the real reading to estimate energy losses._
13. Pertaining to a theoretical, infinitesimal velocity imposed on a mechanical system without violating its constraints; also said of other physical quantities resulting from such a velocity.
   - Simple: Describing a tiny imagined movement in a machine that still obeys the system's limits.
   - _The principle of virtual work introduces a virtual velocity consistent with the system's constraints._
   - _Each virtual displacement must respect the rigid links connecting the components._

## Noun

5. Something simulated in a computer or online; computer-generated reality; specifically, in gambling, a computer simulation of a real sport such as horse racing.
   - Simple: A computer-made version of a real sport, such as a simulated horse race you can bet on.
   - _Between live fixtures, the shop streams virtuals around the clock._
   - _She lost a few dollars on a virtual when the favorite stumbled at the final fence._
7. What is imitated or simulated rather than existing in fact or reality; an instance of such a thing.
   - Simple: The copied or made-up version of something, instead of the real thing.
   - _Theorists often ask whether the virtual shapes our experience as much as the actual world._
   - _A photograph, in her argument, is a virtual that imitates presence without supplying it._
11. A member function of a class that is declared virtual, allowing derived classes to override its behavior.
   - Simple: In programming, a function in a class that child classes can replace with their own version.
   - _She marked the method as a virtual so subclasses could provide their own implementation._
   - _When you call a virtual through a base-class pointer, the runtime selects the correct override._

## Adjective

14. Capable of producing a result; effective or efficacious. *(obsolete)*
   - Simple: Able to bring about a result and to work effectively.
15. Effective through an unseen power alone, without the action of any material or measurable agent. *(obsolete)*
   - Simple: Able to act without any physical or measurable cause, and having unseen power.
16. Having efficacy or power arising from certain natural qualities. *(obsolete)*
   - Simple: Having power or effect that comes from its own natural qualities.
17. Of a plant or other thing, possessing strong healing powers; potent and beneficial. *(obsolete)*
   - Simple: Describes a plant or other thing that has a strong power to heal.
18. Full of virtue; having excellent moral character. *(obsolete)*
   - Simple: Full of virtue and having very good moral character.

## Origin

The adjective comes from Middle English vertual, virtual, from Old French vertüal (modern French virtuel) or from its source, Medieval Latin virtuālis ("of or pertaining to power; having power to produce an effect; morally virtuous"). This traces back to Latin virtūs ("goodness, virtue; manliness"), from vir ("adult male, man"), ultimately from Proto-Indo-European *wiHrós ("man"), possibly from *weyh₁- ("to chase, hunt, pursue"). The noun is derived from the adjective.

Source: DictionaryAI, https://dictionaryai.com/define/virtual (written from Wiktionary data, CC BY-SA 4.0: https://creativecommons.org/licenses/by-sa/4.0/).