1. To some (great or small) extent
   "it was rather cold"; "the party was rather nice"; "the knife is rather dull"; "I rather regret that I cannot attend"; "He's rather good at playing the cello";
   - kind of [informal], kinda [non-standard], sort of [informal]
    
2. In a preferred way
   "I'd rather be in Philadelphia";
   - preferably, sooner
    
3. On the contrary
   "rather than disappoint the children, he did two quick tricks before he left"; "he didn't call; rather, he wrote her a letter";
   - instead
    
4. To a degree (not used with a negative)
   "rather tasty";
   - quite

Encyclopedia: Rather, Elizabeth