Jacen sits next to 5 phonetic neighbors — Jason, Jaden, and Jayson are the closest matches by sound. Most share Jacen's Greek-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"healer"
"bright star"
"thank you, grateful"
"goodness of God"
"surname-to-given-name transfer"
"surname-origin given name"
"precious, supremely valuable"
"elm grove, place of elms"
"swift, victorious"
"swift, graceful"
"son of Hudde (son of Hugh)"
"God is my light, my flame is Yahweh"
"of the wood, forest"
"healer, physician"
"land of Eoghan (Owen)"
"free ruler, powerful peace"
"earthworker (as short for George)"
"son of Rhys, son of the ardent one"
"supplanter (through Jay from Jason/James)"
"homestead by the stream"
"grey, rocky land"
Similar sound: These names share phonetic patterns with Jacen — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Greek origins, giving them the same cultural heritage as Jacen.
Rhythm: Jacen is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.