encephalomalacia

noun

en·​ceph·​a·​lo·​ma·​la·​cia in-ˌsef-ə-lō-mə-ˈlā-sh(ē-)ə 

: softening of the brain due to degenerative changes in nervous tissue (as in crazy chick disease)

encephalomalacic

-mə-ˈlas-ik 

adjective