WordWeb Online

1. Without force or sincere effort
   "smiled thinly"
    
2. Without viscosity
   "the blood was flowing thinly"
   - thin
    
3. In a small quantity or extent
   "spread the margarine thinly over the meat"
   - lightly
    
4. In a widely distributed manner
   "thinly overgrown mountainside"

See also: thin

Antonym: thickly