indistinguishable
1. [ adjective ] exactly alike; incapable of being perceived as different
Synonyms: identical
Examples:

"rows of identical houses" "cars identical except for their license plates" "they wore indistinguishable hats"

Related terms: same
2. [ adjective ] not capable of being distinguished or differentiated
Synonyms: undistinguishable
Examples:

"the twins were indistinguishable" "a colorless person quite indistinguishable from the colorless mass of humanity"

Related terms: distinguishable
Similar spelling:   indistinguishability
  indistinctness