This is the 559th most frequent Lithuanian word.
pagrindinė
Primary; main; principal.
In this sentence, 'pagrindinė' is an adjective describing the noun 'problema' (issue), indicating that it is the primary or most important one.
Pagrindinė šio namo problema yra sena stogo danga.
The main issue of this house is the old roof covering.
Here, 'pagrindinės' is used as an adjective modifying the noun 'mokyklos' (school), specifying it as 'main' or 'primary' (referring to an institution of elementary education).
Mane labiausiai domina pagrindinės mokyklos mokinių pasiekimai.
I am most interested in the achievements of the primary school students.
In this example, 'pagrindinių' functions as an adjective qualifying the noun 'klausimų' (topics/questions) in the genitive plural form, emphasizing their significance.