Source : Webster's Revised Unabridged Dictionary (1913)

Interposition \In`ter*po*si"tion\ (?; 277), n. [L. interpositio
   a putting between, insertion, fr. interponere, interpositum:
   cf. F. interposition. See {Interpone}, {Position}.]
   1. The act of interposing, or the state of being interposed;
      a being, placing, or coming between; mediation.

   2. The thing interposed.

Source : WordNet®

interposition
     n 1: the action of interjecting or interposing an action or
          remark that interrupts [syn: {interjection}, {interpolation},
           {interpellation}]
     2: the act of interposing one thing between or among others