Nouns

(n)slump, slack, drop-off, falloff, falling offa noticeable deterioration in performance or quality“the team went into a slump”, “a gradual slack in output”, “a drop-off in attendance”, “a falloff in quality”
(n)depression, slump, economic crisisa long-term economic state characterized by unemployment and low prices and low levels of trade and investment

Verbs

(v)slump, slouchassume a drooping posture or carriage
(v)slump, slide down, sinkfall or sink heavily“He slumped onto the couch”, “My spirits sank”
(v)slump, fall off, sinkfall heavily or suddenly; decline markedly“The real estate market fell off”
(v)decline, slump, correctfall in value“the stock market corrected”, “prices slumped”