WordWeb Online

1. In a keen or penetrating way
   "she pitied her sister acutely"; "acutely aware";
   - keenly
    
2. Having a rapid onset
   "an acutely debilitating virus"
    
3. Changing suddenly in direction and degree
   "the visor was acutely peaked"; "her shoes had acutely pointed toes";
   - sharply, sharp
    
4. In a shrewd manner
   "he was acutely insightful";
   - astutely, shrewdly, sagaciously, sapiently, perspicaciously, advisably

Antonym: chronically