1. To a severe or serious degree
   "fingers so badly frozen they had to be amputated"; "badly injured";
   - severely, gravely, seriously, critically
    
2. In a poor or unsatisfactory manner; not well
   "the car runs badly"; "he performed badly on the exam";
   - ill, poorly
    
3. Without skill or in a displeasing manner
   "she writes badly"; "I think he paints very badly"
    
4. Evilly or wickedly
   "treated his parents badly"; "to steal is to act badly"
    
5. With great intensity (‘bad’ is a nonstandard variant for ‘badly’)
   "the injury hurt badly"; "the buildings were badly shaken";
   - bad
    
6. Very much; strongly
   "I wanted it badly enough to work hard for it"; "the cables had sagged badly"; "they were badly in need of help";
   - bad
    
7. In a disadvantageous way; to someone's disadvantage
   "the venture turned out badly for the investors";
   - disadvantageously
    
8. Unfavourably or with disapproval
   "thought badly of him for his lack of concern";
   - ill
    
9. With unusual distress, resentment, regret or emotional display
   "conducted himself very badly at the time of the earthquake"; "they took their defeat badly"; "took her father's death badly"

Antonym: advantageously, good [N. Amer], well