Degeneration is a process of decline. Anything that’s getting worse is going through degeneration. A grand old mansion that’s now abandoned and covered with weeds is in a state of degeneration.
When something degenerates, it gets worse in some way, like a house that’s slowly sinking in the mud. This process of decline is called degeneration. The word is from the Latin word degenerare which means "to be inferior to one's ancestors.” Ouch. Now degeneration refers to anything in a state of decline, such as a friendship that was strong and now barely exists.