Diffusion rhymes with:
rediffusion, rediffusion, confusion, fusion, infusion, profusion, rediffusion, reperfusion, transfusion, confusion, fusion, infusion, profusion, rediffusion, reperfusion, transfusion
Diffusion sounds like:
d'aubuisson, davignon, davison, davisson, devaughn, division, divison, dobkin, dobson, dopson, dubuisson