This is the 2448th most frequent Turkish word.
kalabalık
"Kalabalık" means "crowd" or "crowded" in English.
In this sentence, 'kalabalık' is used as an adjective to describe the city, meaning that it has a lot of people or is very populous.
Bu şehir çok kalabalık.
This city is very crowded.
Here, 'kalabalık' is used as a noun, referring to a group of people gathered together.
Sokakta bir kalabalık gördüm.
I saw a crowd on the street.
In this case, 'kalabalık' is used as an adjective describing the state of the wedding hall being filled with many people.