To slump is to fall or slouch down. It's also a downturn in performance — a struggling ballplayer and a sinking economy are both in a slump. There are many kinds of slumps, but they all involve things going downhill. If you slide down in your chair, you slump. Other slumps are less physical. More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.