1. indistinguishable(s = adj.all) identical - exactly alike; incapable of being perceived as different; "rows of identical houses"; "cars identical except for their license plates"; "they wore indistinguishable hats"
Derived form noun indistinguishability1
2. indistinguishable(a = adj.all) undistinguishable - not capable of being distinguished or differentiated; "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"
Antonym: distinguishable
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]
indistinguishable, adj. (often foll. by from) not distinguishable.
Derivative:
indistinguishableness n. indistinguishably adv.
N identity, sameness, coincidence, coalescence, convertibility, equality, selfness, self, oneself, identification, monotony, tautology, facsimile, homoousia: alter ego, ipsissima verba, same, self, very, one and the same, very thing, actual thing, real McCoy, no other, one and only, in the flesh, identical, self, ilk, the same, selfsame, one and the same, homoousian, coincide, coalescent, coalescing, indistinguishable, one, equivalent, tweedle dee and tweedle dum, much the same, of a muchness, unaltered, identically, on all fours.
N equality, parity, coextension, symmetry, balance, poise, evenness, monotony, level, equivalence, equipollence, equipoise, equilibrium, equiponderance, par, quits, a wash, not a pin to choose, distinction without a difference, six of one and half a dozen of the other, tweedle dee and tweedle dum, identity, similarity, equalization, equation, equilibration, co-ordination, adjustment, readjustment, drawn game, drawn battle, neck and neck race, tie, draw, standoff, dead heat, match, peer, compeer, equal, mate, fellow, brother, equivalent, equal, even, level, monotonous, coequal, symmetrical, coordinate, on a par with, on a level with, on a footing with, up to the mark, equiparant, equivalent, tantamount, indistinguishable, quits, homologous, synonymous, resolvable into, convertible, much at one, as broad as long, neither more nor less, much the same as, the same thing as, as good as, all one, all the same, equipollent, equiponderant, equiponderous, equibalanced, equalized, drawn, half and half, isochronal, isochronous isoperimetric, isoperimetrical, isobath, isobathic, equally, pari passu, ad eundum, caeteris paribus, in equilibrio, to all intents and purposes, it comes to the same thing, it amounts to the same thing, what is sauce for the goose is sauce for the gande.
N invisibility, invisibleness, nonappearance, imperceptibility, indistinctness, mystery, delitescence, concealment, latency, invisible, imperceptible, undiscernible, indiscernible, unapparent, non-apparent, out of sight, not in sight, a perte de vue, behind the scenes, behind the curtain, viewless, sightless, inconspicuous, unconspicuous, unseen &c (see), covert, eclipsed, under an eclipse, dim, mysterious, dark, obscure, confused, indistinct, indistinguishable, shadowy, indefinite, undefined, ill- defined, ill-marked, blurred, fuzzy, out of focus, misty, delitescent, hidden, obscured, covered, veiled (concealed), full many a flower is born to blush unseen.
N indiscrimination, indistinguishability, indistinctness, indistinction, uncertainty, incomparability, indiscriminate, undistinguished, indistinguishable, undistinguishable, unmeasured, promiscuous, undiscriminating, valeat quantum valere potest.