Main entry: indistinguishable, undistinguishable
Definition: not capable of being distinguished or differentiated
Usage: the two specimens are actually different from each other but the differences are almost indistinguishable; the twins were indistinguishable; a colorless person quite indistinguishable from the colorless mass of humanity
Main entry: indistinguishable, identical
Definition: exactly alike; incapable of being perceived as different
Usage: rows of identical houses; cars identical except for their license plates; they wore indistinguishable hats