This is the 1379th most frequent Japanese word.
低下
Decline; deterioration; decrease.
The word '低下' is used to describe a decrease or decline in academic ability.
学力の低下が問題になっています。
The decline in academic ability is becoming a problem.
Here, '低下' is used to refer to the reduction in temperature levels.
温度の低下に注意してください。
Please be aware of the temperature drop.
In this context, '低下' signifies a diminishment in the strength of the immune system.