serious and strict, and showing strong disapproval of someone's behaviour:
sterner penalties for drug offences
stern look/voice/expression etc
'Wait!' I shouted in my sternest voice.
His actions have earned him stern rebukes from human-rights organizations.
to have a strong character and be more determined than other people to succeed in a difficult situation:
Ann, made of sterner stuff than I, refused all offers of help.
—sternness noun [uncountable]