This is the 206th most frequent Serbian word.
четвртак
"Четвртак" means "Thursday" in English.
The word 'четвртак' is used as a subject of the sentence to denote a day of the week.
Данас је четвртак.
Today is Thursday.
Here, 'четвртка' is in the genitive singular case, indicating a repetitive action occurring on Thursdays.
Имам час физике сваког четвртка.
I have a physics class every Thursday.
In this instance, 'четвртак' is in the accusative singular case, relating to a specific day in the week.