virtual
Noun pluralvirtuals (some meanings)
Pluralvirtuals (some meanings)
- 1Existing in effect or essence rather than in actual fact; imitated or simulated.
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.
Similareffective
Note
The core modern sense still carries its origin. Medieval Latin virtualis meant "having power to produce an effect," and Jeremy Taylor in 1653 still explains virtual taking as taking "in virtue or effect." Something virtual has the force of a thing without its formal standing. Its close synonym is de facto. Its opposites are actual, real, true and veritable, which all insist on fact over effect.
- 2Amounting to something for practical purposes though not technically; almost complete or very near.
The factory closure caused a virtual collapse of the town's economy.
His silence on the matter amounted to a virtual admission of guilt.
Note
Here the word measures closeness rather than effect: a virtual army, a virtual surrender, a virtual spectator. It sits before the noun and works much like "nearly." Edmund Burke in 1769 warns that yielding one point would mean a virtual surrender of the whole legislative right. Compared with the "in effect" sense, the stress falls on how near the thing comes, not on what it amounts to.
- 3Operating through a computer or online rather than being physically present.
Most of the conference shifted to a virtual format last year.
The clinic now offers virtual appointments for routine checkups.
Oppositein-person, face-to-face, physical
Note
In this sense the people and services are real, and only the shared room is missing. A virtual personal trainer or a virtual therapy session still involves a human on the other end. Abigail Abrams, writing in 2020, describes hospitals adding video doctors' visits to free beds for coronavirus patients. That sets it apart from the "simulated" computing sense, where the thing itself exists only in software.
- 4Simulated within a computer or online rather than existing as a physical thing.
Architects walked clients through a virtual model of the unbuilt tower.
The headset drops you into a fully virtual landscape.
Oppositereal, physical, actual
Note
Computing's fixed phrases come from this sense: virtual machine, virtual memory, virtual private network. In each, software stands in for something physical that is not really there. Virtual addressing, for instance, lets programs believe in more memory than actually exists. In games and headsets the word names whole simulated worlds, which leads to the noun for simulations.
- 5Something simulated in a computer or online; computer-generated reality; specifically, in gambling, a computer simulation of a real sport such as horse racing.
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.
Note
Betting has made this a countable noun: a virtual is a computer-run horse race or other sporting event. Its result comes from software, not from any real contest, yet it is wagered on like the real thing. In its uncountable use the word sits close to virtual reality itself, meaning the simulated world as a whole rather than one event within it.
- 6Of a class member in programming: able to be overridden by a different implementation in a subclass.
Declaring the method virtual lets each subclass define its own behavior.
A virtual function in the base class is overridden by the derived one.
Note
In code this is as much a keyword as an adjective. A method is declared virtual so that a subclass may replace it. The call is then resolved at run time by the object's actual type, not by the type of the reference used to reach it. The base class sets out the behavior, and each subclass is free to rewrite it.
- 7What is imitated or simulated rather than existing in fact or reality; an instance of such a 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.
Note
With "the" in front, the adjective becomes an abstract noun. It is built like "the real" and "the actual" and is usually set against them in philosophy and media theory. It can also be counted, as in a virtual or several virtuals, when an argument names one simulated thing at a time. The computing noun, used for simulations, is a separate and more concrete use.
- 8In optics, of a focus, point, or image, from which light only appears to come, rather than actually meeting there.
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.
Oppositereal
Note
Optics pairs it strictly with real. A real image forms where rays actually meet and can be caught on a screen. A virtual image sits where rays only seem to come from, as with a reflection behind a plane mirror, so no screen placed there would show it. Virtual focus is the commonest phrase, and a concave lens produces such images.
- 9In physics, describing particles that exist only briefly, their fleeting existence allowed by the Heisenberg uncertainty principle.
Two electrons repel each other by exchanging virtual photons.
A virtual particle borrows energy for a tiny fraction of a second before disappearing.
Note
Particle physics sets these against real particles. Virtual particles are never caught in a detector, yet forces between real particles are pictured as their exchange. The photon is the textbook case, so virtual photon is the phrase most often met. This carries the word's old idea of "in effect, not in fact" down to the smallest scale physics describes.
- 10Describing a quantum state that is intermediate, exists only briefly, and cannot be observed 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.
Note
Where virtual particles are things, this sense describes stages. A virtual state is a waypoint a quantum process passes through between two observable states. It belongs to the calculation, not the laboratory. Theorists say such states lie off the mass shell, meaning they need not satisfy the energy–momentum relation that governs a free particle.
- 11A member function of a class that is declared virtual, allowing derived classes to override its behavior.
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.
Note
This is programmers' shorthand: a virtual is simply a virtual function. The adjective for overridable class members has been clipped into a noun. It is countable, with the plural virtuals, so a base class may declare several virtuals. It keeps all the behavior of the longer phrase, including the run-time choice of which override is called.
- 12Describing 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.
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.
Note
Engineers use it for an idealized figure: the pressure a head of water would deliver if pipes had no friction. A gauge reading always falls short of it, so the virtual value works as a ceiling rather than a prediction. It shares a spirit with virtual displacement and work, since both define a quantity by setting something aside. Here, though, what is set aside is lost energy, not imagined motion.
- 13Pertaining 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.
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.
Note
Mechanics uses the word for a thought experiment. Imagine the system nudged by an infinitesimal amount its constraints allow, then ask what work the forces would do. Virtual displacement and virtual work are the standard phrases, and the principle of virtual work rests on them. Nothing actually moves, since the motion is only a test. That is why the old idea of "in effect, not in fact" fits so well.
- 14Capable of producing a result; effective or efficacious.
Note
This obsolete sense is easy to read backward. When Joseph Moxon in 1683 calls two authors' testimony "a vertual Proof" of John Dee's argument, he means an effective proof, one that does its work. He does not mean an almost-proof. The spelling vertual, inherited from Middle English, is a helpful signal that the older meaning is in play.
- 15Effective through an unseen power alone, without the action of any material or measurable agent.
Note
Early natural philosophy set this sense against substance. Francis Bacon in 1631 explains that water cools air without wetting it because heat and cold make "a virtual transition, without communication of substance," while moisture cannot. Virtual action passes power across without passing matter. The sense is obsolete, but it bridges to the modern idea of something present in effect though absent in fact.
- 16Having efficacy or power arising from certain natural qualities.
[H]is ſenſes flame / Flovv'd from his parts, vvith force ſo virtuall, / It fir'd vvith ſence things meere inſenſuall.
1598, George Chapman, “Third Sestyad”Note
Here the word still means what its Latin source meant, as traced under the "in effect" sense: power that belongs to a thing by nature. Milton's Paradise Lost (1667) has every living kind warmed "by his virtual power." Francis Bacon in 1631 tests whether the virtual heat of wine can ripen an apple. In such texts, read "potent," never "simulated."
- 17Of a plant or other thing, possessing strong healing powers; potent and beneficial.
Note
The healer's narrowing of natural potency: power turned toward curing. Its old equivalent, virtuous, carried the same meaning of "potent," so a virtuous herb was one that healed, not one that behaved well. Neither word should be read through the moral sense here. The usage is obsolete, both literally for plants and in its figurative stretch to other things.
- 18Full of virtue; having excellent moral character.
The moſt in ſoule deiected; the moſt baſe, / And moſt vnſeruiceable weede, vnles / You by your heauenly Influence change his vilenes / Into a vertuall habit fit for vſe.
1607, Thomas Dekker, “The Whore of Babylon.”Similarvirtuous
Note
In this sense the word stood closest to its cousin virtue. Thomas Dekker in 1607 speaks of turning vileness "into a vertuall habit fit for use." George Meredith still reaches for it in 1898, setting "virtual France" beside "the France benevolent, the chivalrous." There it praises a virtuous France. A modern reading of "almost" or "simulated" would turn the poet's tribute into a slight.
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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.