1. Without doubt or question
   "they were clearly lost"; "history has clearly shown the folly of that policy"
    
2. In an intelligible manner; in a way that can be understood
   "the foreigner spoke to us quite clearly";
   - intelligibly, understandably
    
3. Clear to the mind; with distinct mental discernment
   "I could clearly see myself in his situation";
   - distinctly
    
4. Unmistakably; visibly clear; in an evident manner
   "The solution was clearly impossible";
   - obviously, evidently, manifestly, patently, apparently, plainly, plain, obvs [non-standard, informal]
    
5. In an easily perceptible manner
   "could be seen clearly under the microscope";
   - clear

Antonym: unintelligibly

Encyclopedia: Clearly, Gottlieb