Caisen sits next to 4 phonetic neighbors — Cason, Cayson, and Mason are the closest matches by sound. Most share Caisen's Gaelic-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"vigilant in war (via Casey)"
"heroic, kingly"
"possibly from Basque or Persian place names"
"maker or seller of knives"
"of Rudolf Diesel; fuel-powered engine"
"God is gracious"
"made of earth, red earth"
"Italian form of John"
"resolute fortress, determined will"
"rational thought, good judgment"
"settlement near a tree stump"
"sad, sorrowful"
"who is like God"
"dark blue"
"beautiful fragrance"
"stone-like, hard, steadfast"
"son of Thomas, son of the twin"
"fashionable, manner of doing"
"from Thrace"
"beam of light (via Ray)"
Similar sound: These names share phonetic patterns with Caisen — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Gaelic origins, giving them the same cultural heritage as Caisen.
Rhythm: Caisen is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.