This is the 13684th most frequent Russian word.
неоднократные
"Repeated" or "multiple."
The word "неоднократные" is used as an adjective modifying "попытки" (attempts), indicating that the attempts were made multiple times.
Неоднократные попытки убедить его не увенчались успехом.
Repeated attempts to persuade him were unsuccessful.
Here, "неоднократные" describes "визиты" (visits), emphasizing that the visits were frequent.
Ее неоднократные визиты в библиотеку показывали её интерес к чтению.
Her repeated visits to the library showed her interest in reading.
The word "неоднократные" indicates that the "замечания" (remarks) were made several times, underscoring their frequency.