The Collaborative International Dictionary of English v.0.48:

Interfuse \In`ter*fuse"\, v. t. [L. interfusus, p. p. of
   interfundere to pour between; inter between + fundere to
   pour. See Fuse to melt.]
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   1. To pour or spread between or among; to diffuse; to
      scatter.
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            The ambient air, wide interfused,
            Embracing round this florid earth.    --Milton.
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   2. To spread through; to permeate; to pervade. [R.]
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            Keats, in whom the moral seems to have so perfectly
            interfused the physical man, that you might almost
            say he could feel sorrow with his hands. --Lowell.
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   3. To mix up together; to associate. --H. Spencer.
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