Source : Webster's Revised Unabridged Dictionary (1913)

Superpose \Su`per*pose"\, v. t. [imp. & p. p. {Superposed}; p.
   pr. & vb. n. {Superposing}.] [F. superposer. See {Super-},
   and {Pose}.]
   1. To lay upon, as one kind of rock on another.

   2. (Geom.) To lay (a figure) upon another in such a manner
      that all the parts of the one coincide with the parts of
      the other; as, to superpose one plane figure on another.

Source : WordNet®

superpose
     v 1: place (one geometric figure) upon another so that their
          perimeters coincide
     2: place on top of; "can you superimpose the two images?" [syn:
         {superimpose}, {lay over}]