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"
"dark, swarthy"
"winding valley"
"little Aodh (fire deity)"
"fair, white, bright"
"from the moon"
"son of Gilbert, son of Gib"
"territory of Owen"
"bright-headed warrior"
"God exists, gift"
"son of the fiery one"
"descendant of the king"
"winding river"
"luminous, shining"
"God is gracious"
"reputation, esteem"
"outer wall of a castle (bailey)"
"impulsive, little king"
"the color gray"
"little seal"
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.