WordWeb Online

1. To a small degree or extent
   "his arguments were somewhat self-contradictory";
   - slightly, more or less, fractionally, marginally, tad [informal], a bit
    
2. To certain extent or degree
   - reasonably, moderately, pretty [informal], jolly [Brit, informal], fairly, middling, passably, middlingly, averagely

Antonym: immoderately