We don't have synonyms for manx cats yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are manx cat.
(n) :
A domestic cat of a breed that is native to the Isle of Man, principally characterized by the suppression of the tail, and with a short-haired coat and a medium-sized, rounded, cobby body.
(n) :
A domestic cat of a breed that is native to the Isle of Man, principally characterized by the suppression of the tail, and with a short-haired coat and a medium-sized, rounded, cobby body.