Kathyn sits next to 4 phonetic neighbors — Kathryn, Kaitlyn, and Caitlin are the closest matches by sound. Most share Kathyn's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"pure, clear"
"wise counsel, gentle (ewe)"
"nickname, playful diminutive"
"God is gracious"
"honoring God, one who honors God"
"one who follows at the heel"
"broom-covered hill, beacon hill"
"Possibly a variant of Teresa/Therese, meaning to reap or harvest"
"faith"
"fairy"
"of Thor, thunder"
"bright, shining"
"pure"
"moon goddess, famous warrior"
"free person, strong one (via Carla/Carl)"
"Of the sea, warrior; defender of the sea"
Similar sound: These names share phonetic patterns with Kathyn — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Greek origins, giving them the same cultural heritage as Kathyn.
Rhythm: Kathyn is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.