Kingdom sits next to 3 phonetic neighbors — Kingston, Kingsley, and Kinston are the closest matches by sound. Most share Kingdom's Old English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"realm, dominion"
"modern coined name"
"nobleman of the second rank"
"little fire (via Aiden root)"
"absence of conflict, wholeness"
"precious gem, jewel"
"God is my salvation"
"gift of God"
"son of Guy"
"mourner"
"from Lucania, southern Italy"
"son of Morris/Maurice"
"meadow dweller"
"split, torn apart"
"world ruler"
"supplanter (via Jacob/Kobe etymology)"
"variant of Jason"
"my God is light"
"righteousness of God"
Similar sound: These names share phonetic patterns with Kingdom — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Old English origins, giving them the same cultural heritage as Kingdom.
Rhythm: Kingdom is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.