Merriam-Webster Collegiate Dictionary - interpose

 verb  (-posed; -posing)  Etymology: Middle French ~r, from Latin interponere (perfect indicative interposui), from inter- + ponere to put — more at position  Date: 1582  transitive verb  1.  a. to place in an intervening position  b. to put (oneself) between ; intrude  2. to put forth by way of interference or intervention  3. to introduce or throw in between the parts of a conversation or argument  intransitive verb  1. to be or come between  2. to step in between parties at variance ; intervene  3. interrupt  • ~r noun Synonyms:  ~, interfere, intervene, mediate, intercede mean to come or go between. ~ often implies no more than this ~d herself between him and the door. interfere implies hindering noise interfered with my concentration. intervene may imply an occurring in space or time between two things or a stepping in to stop a conflict quarreled until the manager intervened. mediate implies intervening between hostile factions mediated between the parties. intercede implies acting for an offender in begging mercy or forgiveness interceded on our behalf.  Synonym: see in addition introduce.