This is the 13942nd most frequent Turkish word.
mayıstaki
"Mayıstaki" means "the one in May" or "that which is in May."
Here, 'mayıstaki' (in May) modifies the noun 'festival,' specifying the time when the festival occurs.
Mayıstaki festival, her yıl büyük bir coşkuyla kutlanır.
The festival in May is celebrated with great enthusiasm each year.
In this sentence, 'mayıstaki' (in May) describes the noun 'tatil' (holiday), indicating its occurrence time.
Mayıstaki tatil planlarımı şimdiden yapıyorum.
I am already making plans for the holiday in May.
Here, 'mayıstaki' (in May) is used to specify the time of the exam, modifying the noun 'sınav' (exam).