So similar that it's impossible or very difficult to tell the difference between two or more things.
From Latin 'in-' (not) + 'distinguere' (to separate or mark), formed in English using the prefix and root meaning 'cannot be separated or differentiated.' Common in scientific and philosophical discourse.
Identical twins are technically indistinguishable by genetics, yet their fingerprints are different—which fascinates forensic scientists because even nature's perfect copies include tiny variations that make perfect identity impossible.
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