Gerund functioning as an uncountable noun meaning the act of reproving.
Definitions
The act or expression of reproving; a rebuke or censure. Her gentle reproving did little to change his habits.
reprovegerund / present participle Used attributively to describe a look, tone, etc., that conveys disapproval (e.g., "a reproving glance").
Definitions
Expressing disapproval or censure. He felt her reproving stare from across the table.