Kasia sits next to 4 phonetic neighbors — Katya, Cassie, and Kasha are the closest matches by sound. Most share Kasia's Polish-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"pure"
"one who is reborn"
"who is like God"
"youthful, downy-bearded"
"radiant, shining"
"torch, beacon"
"thousand years, millennium"
"little mouse"
"gift of Zeus, power of Zeus"
"radiance, brightness"
"dawn, morning light"
"peace, wholeness"
"pure, unsullied"
"fairy queen (folk etymology)"
"my God is an oath"
"virtuous woman"
Similar sound: These names share phonetic patterns with Kasia — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Greek (katharos) origins, giving them the same cultural heritage as Kasia.
Rhythm: Kasia is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.