This is the 7974th most frequent Polish word.
nck
It seems "nck" is not a word in Polish. It may be a typo or abbreviation.
In this sentence, "nck" is used to refer to singular instances of nights and reflects unique or significant characteristics.
Niektóre nck sprawiły, że nie mogłem zasnąć.
Some nights made it impossible for me to sleep.
Here, "nck" conveys the idea of special nights that stand out due to memorable events or experiences.
Te nck są rzeczywiście niezapomniane.
These nights are truly unforgettable.
In this usage, "nck" describes peaceful and serene times during the nighttime associated with a specific location or activity.