1. Not widely known; especially valued for its uncommonness
   "a rare word"; "rare books"
    
2. Marked by an uncommon quality; especially superlative or extreme of its kind
   "what is so rare as a day in June"; "a rare skill";
   - uncommon
    
3. Not widely distributed
   "rare herbs"; "rare patches of green in the desert"
    
4. Recurring only at long intervals
   "a rare appearance"; "total eclipses are rare events"
    
5. Having low density
   "rare gasses";
   - rarefied, rarified
    
6. (of meat) cooked a short time; still red inside
   "rare roast beef"

Derived forms: rarer, rarest

See also: extraordinary, infrequent, raw, scarce, thin, uncommon

Encyclopedia: Rare, Precious and Beautiful