Katharine sits next to 4 phonetic neighbors — Katherine, Catherine, and Katarina are the closest matches by sound. Most share Katharine's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"pure, clean"
"ewe plus waterfall"
"hazel meadow, clearing of hazel trees"
"opportunity"
"loosening, release"
"bright, handsome"
"nickname form of Adelaide, Addison, Adeline"
"clear, bright"
"of proud heritage"
"son of Emery (surname origin)"
"dear, darling (diminutive)"
"Ireland; from the island of Ireland"
"wise protection and gracious"
"garden of God, God's vineyard"
"flax plant"
"son of Maude (alternative etymology)"
"gift of God"
"pertaining to the sun"
"from the long ridge"
Similar sound: These names share phonetic patterns with Katharine — 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 Katharine.
Rhythm: Katharine is a 3-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.