Mona sits next to 4 phonetic neighbors — Nona, Lona, and Fiona are the closest matches by sound. Most share Mona's Irish-rooted cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"noble one, little noble"
"passage, adventure"
"grey lady"
"radiance, brilliance, splendor"
"heavenly, sky, royal"
"princess, noble one"
"gift of God's grace"
"eternity, immortality"
"guardian, watch mountain"
"dearness, preciousness"
"pure"
"beauty, strength, luxury"
"courageous, spirited (from Irish Raghallach)"
"merry, joyful"
"moon"
"Ash tree settlement"
"descendant of Raighne (Irish clan)"
"noble, kind"
"beautiful and rising"
"mighty with a spear (ger + wald)"
"high ground"
Similar sound: These names share phonetic patterns with Mona — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Irish Gaelic origins, giving them the same cultural heritage as Mona.
Rhythm: Mona is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.