Niam sits next to 3 phonetic neighbors — Niamh, Liam, and Neem are the closest matches by sound. Most share Niam's Irish-rooted cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"bright, radiant"
"dragon, serpent"
"pierces the valley"
"mourning (symbolic)"
"dweller in the valley"
"words of a song"
"from the pool or marsh"
"He has given (divine gift)"
"defender of the army"
"modern invented name"
"hero (cultural/gaming)"
"from Leicester"
"modern invented name, possibly dark one"
"God has been gracious"
"place of alder trees"
"remembered by God"
"cross"
"praised (from Judah/Yehuda)"
"son of Case; from the marsh"
"brave spear, strong with a spear"
Similar sound: These names share phonetic patterns with Niam — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Old Irish origins, giving them the same cultural heritage as Niam.
Rhythm: Niam is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.