The torus (French: tore) is one of the figures that Lacan analyses in his study of topology.
In its simplest form, it is a ring, a three-dimensional object formed by taking a cylinder and joining the two ends together.
Lacan's first reference to the torus dates from 1953, but it is not until his work on topology in the 1970s that it begins to figure prominently in his work.
The topology of the torus illustrates certain features of the structure of the subject:
One important feature of the torus is that its centre of gravity falls outside its volume, just as the centre of the subject is outside himself; he is decentred, excentric.
Another property of the torus is that "its peripheral exteriority and its central exteriority constitute only one single region."
This illustrates the way that psychoanalysis problematises the distinction between 'inside' and 'outside.' (see extimacy).
6. Lacan exemplifies the intrication of demand and desire with two intertwined toruses in Seminar IX, Identification, where a circle drawn around the tube-like surface of one torus (the circle of demand) coincides with the smallest circle around the central void in the other (the circle of desire).