WordWeb Online

1. To a moderately sufficient extent or degree
   "he is fairly clever with computers"
   - reasonably, moderately, pretty, jolly [Brit], somewhat, middling, passably, averagely, middlingly
    
2. Without favouring one party, in a fair evenhanded manner
   "deal fairly with one another"
   - fair, evenhandedly
    
3. In conformity with the rules or laws and without fraud or cheating
   "they played fairly"
   - fair, clean

See also: fair

Antonym: unfairly