fallend
falling / decreasing
Moving downward or decreasing in value, amount, or intensity.
Die fallenden Blätter kündigten den Herbst an.
The falling leaves announced the arrival of autumn.

falling / decreasing
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falling / decreasing
Moving downward or decreasing in value, amount, or intensity.
Die fallenden Blätter kündigten den Herbst an.
The falling leaves announced the arrival of autumn.

'Fallend' (falling/decreasing) is the present participle of the verb 'fallen' (to fall). It is used like an adjective and describes an ongoing action or process of moving downward or decreasing.
Vorsicht, da ist ein fallender Ast!
Careful, there is a falling branch!
When 'fallend' (falling/decreasing) stands before a noun, it is declined like any other adjective. It agrees with the noun in gender, case, and number.
Wir beobachten die fallenden Temperaturen mit Sorge.
We are watching the falling temperatures with concern.
In economic contexts, 'fallend' (falling) is often combined with terms such as 'Kurse' (stock prices/rates), 'Preise' (prices), 'Zinsen' (interest rates), or 'Tendenz' (trend/tendency).
Anleger reagieren nervös auf die fallenden Kurse.
Investors are reacting nervously to the falling stock prices.
The meaning in the mathematical context is technical language. It is used to describe the behavior of functions or sequences and is usually found in academic or school texts.
Diese Kurve ist streng monoton fallend.
This curve is strictly monotonically decreasing.
increasingly / waxing
'zunehmend' and 'fallend' both describe a change over time, but in opposite directions. 'zunehmend' means that something becomes more, stronger, or more frequent. 'fallend' means that something goes downward or becomes less, for example a value or an amount. The words can be confused when talking about numbers, prices, or developments. Pay attention to the direction: with 'zunehmend', things go up; with 'fallend', they go down.

Beim Arzt freut sich Ali, weil sein Blutdruck fallend ist.
At the doctor's office, Ali is pleased because his blood pressure is falling.
Im Sommer wird die Hitze in der Stadt zunehmend belastend.
In summer, the heat in the city becomes increasingly oppressive.