The Collaborative International Dictionary of English v.0.48:

Softening \Sof"ten*ing\,
   a. & n. from Soften, v.
   [1913 Webster]

   Softening of the brain, or Cerebral softening (Med.), a
      localized softening of the brain substance, due to
      hemorrhage or inflammation. Three varieties, distinguished
      by their color and representing different stages of the
      morbid process, are known respectively as red, yellow, and
      white, softening.
      [1913 Webster]