rare

not widely known; especially valued for its uncommonness; "a rare word"; "rare books"

recurring only at long intervals; "a rare appearance"; "total eclipses are rare events"

not widely distributed; "rare herbs"; "rare patches of green in the desert"

having low density; "rare gasses"; "lightheaded from the rarefied mountain air"

marked by an uncommon quality; especially superlative or extreme of its kind; "what is so rare as a day in June"-J.R.Lowell; "a rare skill"; "an uncommon sense of humor"; "she was kind to an uncommon degree"

(of meat) cooked a short time; still red inside; "rare roast beef"