Today the words [authentic and genuine] are interchangeable in most sentences, but a couple of distinctions do exist. First, 'authentic' is off-target when the sense is 'substantial'. . . . Second, 'authentic' is an awkward choice when the sense is 'since

Today the words [authentic and genuine] are interchangeable in most sentences, but a couple of distinctions do exist. First, 'authentic' is off-target when the sense is 'substantial'. . . . Second, 'authentic' is an awkward choice when the sense is 'sincere'. . . . The OED notes that late-18th-century theologians tried to differentiate the words, arguing that a book is 'authentic' if its content is accurate, and 'genuine' if it is correctly attributed to the writer. The point, weak as it was to begin with, has been preserved in some later usage guides.