Indistinguishable means impossible to tell apart or see any difference between. When two things are indistinguishable, they look, sound, or seem exactly the same to you, even if you examine them carefully.

Identical twins are often indistinguishable to people who don't know them well. Two paint samples might be indistinguishable in color. A talented voice actor might make their imitation of a famous person indistinguishable from the real thing. In science, if the results of two experiments are indistinguishable, that means they produced the same outcome.

Being indistinguishable isn't always about being physically identical. Two plans might be practically indistinguishable if they would produce the same results, even if the details differ slightly. A forgery aims to be indistinguishable from the original artwork. The more indistinguishable a fake becomes from the real thing, the harder it is to spot the deception.