Seamus sits next to 3 phonetic neighbors — James, Shamus, and Hamish are the closest matches by sound. Most share Seamus's Irish-rooted cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"supplanter"
"cloud"
"brave spear, strong with a spear"
"creative elaboration of Finn"
"son of Gilbert, son of Gib"
"from the mouth of the Roe river"
"wealthy protector"
"descendant of Ceallach"
"broad valley"
"God exists, gift"
"territory of Owen"
"reddish-brown (color)"
"strong-willed warrior"
"God is gracious"
"bright, radiant"
"follower of Dionysus, god of wine"
"son of the fiery one"
"winding river"
"green river, fresh water"
Similar sound: These names share phonetic patterns with Seamus — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Hebrew via Irish origins, giving them the same cultural heritage as Seamus.
Rhythm: Seamus is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.