The specular image refers to the reflection of one's own body in the mirror, the image of oneself which is simultaneously oneself and other -- the "little other".
It is by identifying with the specular image that the infant first begins to construct its ego in the mirror stage.
Even when there is no real mirror, the infant sees its behaviour reflected in the imitative gestures of an adult or another child; these imitative gestures enable the other person to function as a specular image.
The human being is completely captivated by the specular image.
This is the basic reason for the power of the imaginary in the subject.
There are certain things which have no specular image, which are not "specularizable."
These are the phallus, the erogenous zones, and objet petit a.