The Collaborative International Dictionary of English v.0.48:

Diffuse \Dif*fuse"\, v. t. [imp. & p. p. Diffused; p. pr. &
   vb. n. Diffusing.] [L. diffusus, p. p. of diffundere to
   pour out, to diffuse; dif- = dis- + fundere to pour. See
   Fuse to melt.]
   To pour out and cause to spread, as a fluid; to cause to flow
   on all sides; to send out, or extend, in all directions; to
   spread; to circulate; to disseminate; to scatter; as to
   diffuse information.
   [1913 Webster]

         Thence diffuse
         His good to worlds and ages infinite.    --Milton.
   [1913 Webster]

         We find this knowledge diffused among all civilized
         nations.                                 --Whewell.

   Syn: To expand; spread; circulate; extend; scatter; disperse;
        publish; proclaim.
        [1913 Webster]

WordNet (r) 3.0 (2006):

diffusing
    adj 1: spreading by diffusion [syn: diffusing(a), diffusive,
           dispersive, disseminative]