This is the 9791st most frequent Polish word.
zmęczenie
"Zmęczenie" means "fatigue" or "tiredness" in English.
Here, 'zmęczenie' refers to physical exhaustion experienced after an effort or exertion.
Po długim biegu poczuł zmęczenie.
After a long run, he felt fatigue.
In this sentence, 'zmęczenie' is used to describe a general tiredness caused by lack of rest or sleep.
Zmęczenie po nieprzespanej nocy wpływa na moją koncentrację.
Fatigue after a sleepless night affects my concentration.
This usage signifies a prolonged state of tiredness, often viewed as a medical condition that requires attention.