in general, signifies the scattering or dissipating something. Hence

in Optics, is the same with the divergency of the rays of light.

Point of Disperession, in Dioptries, the point from which refracted rays begin to diverge, where their refraction renders them divergent.

Disperession of Inflammation, in Medicine and Surgery, is the removing the inflammation, and restoring the inflamed part to its natural state.