" insuperable "

1: incapable of being defeated, overcome, or subdued;

  * e.g., " ... the building project ran into insuperable financial difficulties and had to be scrapped "

•  Synonyms : 

•  bulletproof,

•  impregnable,

•  indomitable,

•  insurmountable,

•  invincible,

•  invulnerable,

•  unbeatable,

•  unconquerable,

•  unstoppable

•  Antonyms : 

•  superable,

•  surmountable,

•  vincible,

•  vulnerable

2: incapable of being solved or accomplished;

  * e.g., " ... insuperable problems have arisen which make it very unlikely that we will ever finish this project "

•  Synonyms : 

•  hopeless,

•  impossible,

•  insoluble,

•  insolvable,

•  unattainable,

•  undoable,

•  unrealizable,

•  unsolvable

•  Antonyms : 

•  achievable,

•  attainable,

•  doable,

•  feasible,

•  possible,

•  realizable,

•  resolvable,

•  soluble,

•  workable