This name is not immediately suggestive of an etymology. Perhaps something like the root suggested for LAMAN, with the second vowel a changing to an o by the Canaanite shift (/ā/>/ō/), and with 1c.s. pronominal suffix /ī/ or a gentilic ending /ī/.
Reynolds & Sjodahl first connected LAMONI to LAMAN, though without explaining how the two were related (R&S, 26). The connection was made again, but this time the gentilic ī ending was suggested (JAT & RFS), similar to the gentilic “ISRAELITE.”
Deseret Alphabet: 𐐢𐐁𐐣𐐄𐐤𐐌 (leɪmoʊnaɪ), 𐐢𐐁𐐣𐐃𐐤𐐌 (leɪmɔːnaɪ)
- Robert F. Smith “Some ‘Neologisms’ from the Mormon Canon,” 1973 Conference on the Language of the Mormons, May 31, 1973 (Provo: BYU Language Research Center, 1973), 65 n. 21, online at https://www.scribd.com/document/363522963/SOME-NEOLOGISMS-FROM-THE-MORMON-CANON .