(adj) not capable of being distinguished or differentiated, Syn. undistinguishable, Ant. distinguishable, Example: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
(adj) exactly alike; incapable of being perceived as different, Syn. indistinguishable, Example:rows of identical houses; cars identical except for their license plates; they wore indistinguishable hats
The Collaborative International Dictionary of English (GCIDE) v.0.53 Collaborative International Dictionary (GCIDE)
a. Not distinguishable; not capable of being perceived, known, or discriminated as separate and distinct; hence, not capable of being perceived or known; as, in the distance the flagship was indisguishable; the two copies were indisguishable in form or color; the difference between them was indisguishable. [ 1913 Webster ]