We don't have synonyms for black swans yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are black swan, black beans and black sand.
(n) :
(figurative) Something believed impossible or not to exist, especially if an example is subsequently found; also, something extremely rare; a rara avis.
(n) :
(figurative) (specifically, also attributive) A rare and hard-to-predict event with major consequences.
(n) :
Cygnus atratus, a swan with black plumage and a red bill which is endemic to Australia.
(n) :
(figurative) Something believed impossible or not to exist, especially if an example is subsequently found; also, something extremely rare; a rara avis.
(n) :
(figurative) (specifically, also attributive) A rare and hard-to-predict event with major consequences.
(n) :
Cygnus atratus, a swan with black plumage and a red bill which is endemic to Australia.