The name could be a hypocoristicon based on ʿmm, a common Semitic kinship term meaning variously “people, clan, paternal uncle, grandfather” (HALOT, 710) appearing in several biblical PNs, e.g., Ammiel, Ammihud, Amram, and Amraphel, plus the hypocoristic ending -on , such as the biblical PNs Amnon and Sampson or the West Semitic PN * ŝšamaʿ-on 
It is also possible that AMMON is derived from the HEBREW root ʾmn, meaning “master workman; architect; firmness, faithfulness” . But this etymology does not account for the doubling of the m. As a hypocoristicon the name could mean “[my god is] faithfulness.” See the biblical PN Amon, carried by a Judean king (2 Kings 21 passim, etc.) (JAT and RFS). Compare from the same root the Amorite PN a-ma-nu-um etc. 
The biblical gentilic AMMON is related by Genesis 19:38 to the root ʿmm. Thus, though the Book of Mormon name probably does not derive from the gentilic, etymologically the two are related (JAT, RFS).
EGYPTIAN imn, originally from southern EGYPT, is the most common name of the later EGYPTIAN Empire. Nibley notes also that AMMON is the most common name in the EGYPTIAN Empire. Nibley sees this name in other Book of Mormon names, i.e., AMINADAB, AMINADI, AMNIHU, AMNOR, Helamon (HELAMAN), etc. Nibley’s connection of AMMON to Hem is perhaps his best evidence that this is the correct etymology. In EGYPT, the high priest of AMMON was called ntr h.m tp, “chief servant of the God,” while in the Book of Mormon, the name of the earlier AMMON is Hem, hence “servant” in EGYPTIAN. Were this a single occurrence, we might ignore it, but Nibley has shown connections between other such pairs of names in EGYPT and the Book of Mormon. EGYPTIAN imn (variously transliterated Amun, Amen, Amon, AMMON; Greek 'ammôn’, Coptic amoun) is the name of the chief god of Thebes, capital of Upper EGYPT. It has been pointed out, in this connection, that the LAMANITE king LAMONI thought AMMON to be the “Great Spirit.” The name comes from the root mn or imn, “establish, make firm; be firm, remain; eternal.” EGYPTIAN imn also means “right, west, westward,” and refers to the kingdom of the dead (imn.t, imny.t, Coptic emnt, amnte, etc.), which can be compared with HEBREW ymyn, “right, right hand, south, southward” (RFS).
Cf. Book of Mormon AMMONIHAH
Once separate entry that seemed to fit under AMMON
See also Ammon / Ammen Variant
The variant Amon suggests a different etymology. The occurrence of this name in the Printer's Manuscript of Mosiah 21:28 may be an example of haplography. If not, then it is to be compared with the biblical PN Amon, and would mean "is faithful" from a qatol form of ʾmn, "craftsman; faithfulness; truth," 
See Michael V. Fox, "mon Again," JBL 115:4 (Winter 1996): 699-702. This is about Proverbs 8:30a, and the conclusion is that it is an "infinitive absolute sometimes functions as an adverbial complement." and that 30a means "Lady Wisdom is declaring that while God was busy creating the world, she was nearby, growing up like a child in his care." P. 702.
Deseret Alphabet: 𐐈𐐣𐐊𐐤 (æmʌn)
- Noth, Martin. Die israelitischen Personennamen im Rahmen der gemeinsemitischen Namengebung. (Beiträge zur Wissenschaft vom Alten und Neuen Testament, III, 10. Stuttgart, 1928; Reprint: Hildesheim: Georg Olms, 1966.) p. 38* (Is this really so?)
- Coogan, Michael David. West Semitic Personal Names in the Marašû Documents. (Harvard Semitic Monographs 7. Missoula, Montana: Scholars Press, 1976) , p. 35.
- Brown, F., S. Driver, and C. Briggs, eds. A Hebrew and English Lexicon of the Old Testament. Oxford: Clarendon, 1968, and HALOT; see Proverbs 8:30
- Gelb, I.J. Computer-Aided Analysis of Amorite. (Assyriological Studies, 21. Chicago: Oriental Institute, 1980) p. 235.
- NIbley, Hugh. Lehi in the Desert., John W. Welch, Darrell L. Matthews, and Stephen R. Callister, eds. (vol. 5 of The Collected Works of Hugh Nibley; Salt Lake City/Provo: Deseret Book/FARMS, 1988), 25.
- NIbley, Hugh, An Approach to the Book of Mormon. (Salt Lake City: Deseret Book/Provo, Utah: Foundation for Ancient Studies, 1988), 286-287.
- Reynolds,George, Commentary on the Book of Mormon, vol. VII., P. C. Reynolds, ed. (SLC: Deseret Book, 1955-1961), 380.
- Zadok, Ran. Notes on Biblical and Extra Biblical Onomasticon p. 115.