Admonitory
/ədˈmɑːnɪtɔːri/
Definition 1 of 1
Pro Tip 1/3Behavior Correction
Used when someone with authority warns others to improve behavior or face consequences. 
Her mother's admonitory speech about her curfew reminded her to come home earlier.
Pro Tip 2/3Subtle Warning
It expresses disapproval subtly and suggests that something negative may happen if ignored. 
With an admonitory note in her voice, the librarian indicated it was time to leave.
Pro Tip 3/3Not Always Verbal
Can be non-verbal like a stern look or gesture that conveys a warning to someone. 
He raised an admonitory finger to his lips, signaling the need for silence.