Quick definitions from WordNet (rare)
▸ adjective: marked by an uncommon quality; especially superlative or extreme of its kind ("What is so rare as a day in June-J.R.Lowell")
▸ adjective: having low density ("Rare gasses")
▸ adjective: not widely distributed ("Rare herbs")
▸ adjective: not widely known; especially valued for its uncommonness ("A rare word")
▸ adjective: (of meat) cooked a short time; still red inside ("Rare roast beef")
▸ adjective: recurring only at long intervals ("A rare appearance")
▸ Also see rare
▸ adjective: marked by an uncommon quality; especially superlative or extreme of its kind ("What is so rare as a day in June-J.R.Lowell")
▸ adjective: having low density ("Rare gasses")
▸ adjective: not widely distributed ("Rare herbs")
▸ adjective: not widely known; especially valued for its uncommonness ("A rare word")
▸ adjective: (of meat) cooked a short time; still red inside ("Rare roast beef")
▸ adjective: recurring only at long intervals ("A rare appearance")
▸ Also see rare