This is the 356th most frequent Vietnamese word.
chẳng
"Chẳng" means "not" or "no" and is used for negation or emphasis.
The word "chẳng" is used here as a negation, similar to the English "did not" to indicate that an action did not occur.
Tôi chẳng ăn sáng hôm nay.
I did not eat breakfast today.
In this sentence, "chẳng" is part of an expression "chẳng lẽ" which conveys a rhetorical question or disbelief.
Chẳng lẽ cô ấy không đến sao?
Isn't she coming?
Here, "chẳng" acts to contrast or negate a behavior, implying the absence of a consideration.