intransitive verb

1. to fall, sink, or collapse, esp. suddenly or heavily
2. to decline suddenly, as in value, activity, etc.
3. to have a drooping posture or gait

Etymology: prob. < or akin to MLowG slumpen, to come about by accident: for IE base see limp

noun

1. a sudden or sharp fall
2. a decline in business activity, prices, etc.
3. a drooping posture or gait
4. ☆ an extended period during which a player, team, worker, etc. is below normal in performance