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"
"chariot boy"
"dark, swarthy"
"little seal"
"land of Eoghan (Owen)"
"famous through noble birth"
"son of the earth"
"Harry's son, son of the ruler"
"little poet, little philosopher"
"descendant of Aodh (fire)"
"from the mouth of the Roe river"
"champion"
"no one equals God"
"bright, radiant"
"descendant of the king"
"creative elaboration of Finn"
"from the Roman gens Terentia"
"reputation, esteem"
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.