Sentence:  Of course the hymn has come to us from somewhere else, but I do not know from where; and the average native of our village firmly believes that it is indigenous to our own soil—which it can not be, unless it deals in <WSD>hyperbole</WSD>, for the nearest approach to a river in our neighborhood is the village pond. 
Meaning of the word marked with <WSD> tags:  Deliberate or unintentional overstatement, "particularly" extreme overstatement.