The difference between "to plunge", " to plummet" and " to slump"

Question

I know they all mean to sudden fall but what is the difference when it comes to context we use in?

Industrial production fell to its weakest growth since the depths of the global financial crisis, while the property market, a pillar of the economy, slumped.

This year profits plunged by 40%.

The shot bird plummeted from the sky

Share prices plummeted to an all-time low.

Her spirits plummeted at the thought of meeting him again.

The jet plummeted into a row of houses.

Profits slumped to under $250 million.

Car ​sales have slumped ​dramatically over the past ​year.

My question are :

1.In the business sense , do you think there is a difference in terms of severity? Can we say for example if we use the word plummet ,we mean the sales numbers fall to zero whereas if we use the word plump sales number fell but not that bad or zero.

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2.I had read before that one of them has a meaning like falling by tumbling, I don't remember now. For example like in the video, not falling from a precipice directly.

https://www.youtube.com/watch?v=P7vte1epVpE

For example :

I ​lost my ​footing and tumbled down the ​stairs. ( from Cambridge Dictionary Online)

Can we say :

I ​lost my ​footing and plummet / slumped / plunged down from the ​stairs.

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3.Which words would be appropriate to use for the graphs below by assuming the fall in the graph in the right takes in a long period.

Answer 1

All three words can stand in for fall but they each have different connotations.

Plummet is often used for objects falling rapidly from a great height. A shot bird plummets. Although it derives from an Old French word for a plumb bob, its association with birds is strengthened by its resemblance to plumage. If I heard that stocks had plummeted I might assume prices were previously very high. Strictly, one would not plummet down stairs as stairs are not vertical, but I suppose it might work as exaggeration.

Plunge implies falling or thrusting into something. One might plunge into a pool or plunge a dagger into someone. This verb is more likely than plummet to suggest intent, though it is not always used that way.

Slump is a wonderful word, with poetic connections to slip, slide, slouch and lump. It suggests something of such considerable mass that it cannot maintain its form and structure under the force of gravity. Things may slump quickly or slowly, but they slump into (relative) immobility. Things that slump rarely spring back up.

If I heard something had tumbled I might suppose the fall was not smooth but irregular and uncontrolled.

Answer 2

1)All the terms you suggest are correct; as for usage the expression to fall appears to be the more common as Ngram shows. To me "to plummet" is the verb that has a stronger connotation compared to the others.

• To decline suddenly and steeply: Stock prices plummeted. (AHD)

2) A common alternative to tumble down the stairs, is to fall down the stairs, other options are possible but are less commonly used, see Ngram.

3)To describe the price movement in the right chart, you might refer to it as constant fall in prices through a lond period.