Not a whit
Definition 1 of 1
Pro Tip 1/3Archaic Tone
Used in historical or literary contexts to sound old-fashioned or formal. 
Though he begged for forgiveness, she felt not a whit of sympathy.
Pro Tip 2/3Emphasizing Negation
Strengthens the sentiment of 'not at all', used to emphasize the absence of something. 
He did not a whit understand her feelings, leaving her frustrated.
Pro Tip 3/3Subtle Harshness
Can convey a subtle sense of dismissiveness or indifference when used in context. 
The critic's harsh comments affected the artist not a whit.