Definitions:

1. In a piercing manner, with penetrating force or effect, or sharply. ADVERB
   • The weather remained piercingly hot.
2. In a way that seems to notice things about another person that would normally be noticed, especially in a way that makes that person feel anxious or embarrassed. ADVERB
   • She looked at him piercingly.

Synonyms:

• acutely
• distressingly
• harshly
• keenly
• Poignantly
• Sharply