Some anti-LDS critics of the Book of Mormon have raised the question as to how Jacob could possibly have used such a word as adieu when this word clearly comes from the French language, which was not developed until hundreds of years after the time of Jacob. Such critics evidently overlook the fact that the Book of Mormon is translation literature, and Joseph Smith felt free in his translation to use any words familiar to himself and his readers that would best convey the meaning of the original author.
It is interesting to note that there is a Hebrew word Lehitra’ot, which has essentially the same meaning in Hebrew as the word adieu has in French. Both of these words are much more than a simple farewell; they include the idea of a blessing.
Would it be unreasonable to remind these critics that none of the words contained in the English translation of the book of Jacob were used by Jacob himself? These words all come from the English language, which did not come into existence until long after Jacob’s time!
(Daniel H. Ludlow, A Companion to Your Study of the Book of Mormon, p. 163)