Dermot sits next to 4 phonetic neighbors — Dermott, Diarmuid, and Dermit are the closest matches by sound. Most share Dermot's Irish-rooted cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"universe, world"
"one who has taken refuge"
"Border land by the meadow"
"holly tree, evergreen plant with red berries"
"son of Edward"
"dawn, son of dawn"
"place of the small wooden dishes"
"free one, Frankish person"
"lord of the marches, borderlands nobleman"
"island of roses"
"Royal meadow; kings clearing"
"short form of Critias"
"dweller near the holly trees"
Similar sound: These names share phonetic patterns with Dermot — similar vowel sounds, consonant clusters, or rhythm.
Rhythm: Dermot is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.