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3 definitions found
 for Virtual image
From The Collaborative International Dictionary of English v.0.48 :

  Image \Im"age\ ([i^]m"[asl]j; 48), n. [F., fr. L. imago,
     imaginis, from the root of imitari to imitate. See Imitate,
     and cf. Imagine.]
     1. An imitation, representation, or similitude of any person,
        thing, or act, sculptured, drawn, painted, or otherwise
        made perceptible to the sight; a visible presentation; a
        copy; a likeness; an effigy; a picture; a semblance.
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              Even like a stony image, cold and numb. --Shak.
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              Whose is this image and superscription? --Matt.
                                                    xxii. 20.
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              This play is the image of a murder done in Vienna.
                                                    --Shak.
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              And God created man in his own image. --Gen. i. 27.
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     2. Hence: The likeness of anything to which worship is paid;
        an idol. --Chaucer.
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              Thou shalt not make unto thee any graven image, . .
              . thou shalt not bow down thyself to them. --Ex. xx.
                                                    4, 5.
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     3. Show; appearance; cast.
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              The face of things a frightful image bears.
                                                    --Dryden.
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     4. A representation of anything to the mind; a picture drawn
        by the fancy; a conception; an idea.
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              Can we conceive
              Image of aught delightful, soft, or great? --Prior.
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     5. (Rhet.) A picture, example, or illustration, often taken
        from sensible objects, and used to illustrate a subject;
        usually, an extended metaphor. --Brande & C.
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     6. (Opt.) The figure or picture of any object formed at the
        focus of a lens or mirror, by rays of light from the
        several points of the object symmetrically refracted or
        reflected to corresponding points in such focus; this may
        be received on a screen, a photographic plate, or the
        retina of the eye, and viewed directly by the eye, or with
        an eyeglass, as in the telescope and microscope; the
        likeness of an object formed by reflection; as, to see
        one's image in a mirror.
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     Electrical image. See under Electrical.
  
     Image breaker, one who destroys images; an iconoclast.
  
     Image graver, Image maker, a sculptor.
  
     Image worship, the worship of images as symbols; iconolatry
        distinguished from idolatry; the worship of images
        themselves.
  
     Image Purkinje (Physics), the image of the retinal blood
        vessels projected in, not merely on, that membrane.
  
     Virtual image (Optics), a point or system of points, on one
        side of a mirror or lens, which, if it existed, would emit
        the system of rays which actually exists on the other side
        of the mirror or lens. --Clerk Maxwell.
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From The Collaborative International Dictionary of English v.0.48 :

  Virtual \Vir"tu*al\ (?; 135), a. [Cf. F. virtuel. See Virtue.]
     1. Having the power of acting or of invisible efficacy
        without the agency of the material or sensible part;
        potential; energizing.
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              Heat and cold have a virtual transition, without
              communication of substance.           --Bacon.
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              Every kind that lives,
              Fomented by his virtual power, and warmed. --Milton.
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     2. Being in essence or effect, not in fact; as, the virtual
        presence of a man in his agent or substitute.
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              A thing has a virtual existence when it has all the
              conditions necessary to its actual existence.
                                                    --Fleming.
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              To mask by slight differences in the manners a
              virtual identity in the substance.    --De Quincey.
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     Principle of virtual velocities (Mech.), the law that when
        several forces are in equilibrium, the algebraic sum of
        their virtual moments is equal to zero.
  
     Virtual focus (Opt.), the point from which rays, having
        been rendered divergent by reflection of refraction,
        appear to issue; the point at which converging rays would
        meet if not reflected or refracted before they reach it. 
  
     Virtual image. (Optics) See under Image.
  
     Virtual moment (of a force) (Mech.), the product of the
        intensity of the force multiplied by the virtual velocity
        of its point of application; -- sometimes called virtual
        work.
  
     Virtual velocity (Mech.), a minute hypothetical
        displacement, assumed in analysis to facilitate the
        investigation of statical problems. With respect to any
        given force of a number of forces holding a material
        system in equilibrium, it is the projection, upon the
        direction of the force, of a line joining its point of
        application with a new position of that point indefinitely
        near to the first, to which the point is conceived to have
        been moved, without disturbing the equilibrium of the
        system, or the connections of its parts with each other.
        Strictly speaking, it is not a velocity but a length.
  
     Virtual work. (Mech.) See Virtual moment, above.
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From WordNet (r) 3.0 (2006) :

  virtual image
      n 1: a reflected optical image (as seen in a plane mirror)

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