Dillan sits next to 4 phonetic neighbors — Dylan, Dillon, and Declan are the closest matches by sound. Most share Dillan's Welsh cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"great tide, sea flow"
"sheltered bay, cove"
"creative American coinage"
"honorable"
"modern invented name, lively"
"hill"
"the Lord is my God"
"servant of a noble, warrior retainer"
"queen of the gods"
"modern coinage inspired by Owen/Cowan"
"one who ropes (cowboy)"
"enclosed pasture by a river"
"from Hugh's meadow, Hucc's woodland clearing"
"from the mountains"
"the shining one"
"son of Thomas, son of the twin"
"gift of God"
"God strengthens, God will strengthen"
"land of Eoghan (Owen)"
"dweller by the mills, mill worker"
Similar sound: These names share phonetic patterns with Dillan — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Welsh origins, giving them the same cultural heritage as Dillan.
Rhythm: Dillan is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.