Question: What is the meaning of Anti-Nephi-Lehies?
Answer: Lamanites, converted through the missionary labors of the sons of Mosiah and their companions, took upon themselves the name Anti-Nephi-Lehies.
“And it came to pass that they called their names Anti-Nephi-Lehies; and they were called by this name and were no more called Lamanites.” (Alma 23:17)
Book of Mormon scholars suggest a variety of definitions.
Hugh Nibley suggests “a Semitic and common Indo-European root corresponding to anti that means ‘in the face of’ or ‘facing,’ as of one facing a mirror, and by extension ‘one who imitates.’”
Stephen Ricks suggests, “The name ‘Anti’ of Anti-Nephi-Lehies may be a reflex of the Egyptian nty ‘he of, the one of.’ Thus, rather than having the sense ‘against,’ it has the meaning of ‘the one of Nephi and Lehi.’”
Source: 400 Questions and Answers About the Book of Mormon by Susan Easton Black, p. 159