Sidney sits next to 4 phonetic neighbors — Sydney, Sidney, and Cydney are the closest matches by sound. Most share Sidney's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"from Saint Denis"
"place of lime trees"
"from Clare (Suffolk)"
"blind"
"modern creative name construction"
"genuine, bold"
"cross, crossroads"
"spear, acquired"
"the brave ones, the warriors"
"from the town, settlement"
"prince (from Arabic amir root)"
"son of Ivar (yew warrior)"
"hill, high ground"
"free man, warrior"
"divine bear"
"difficult journey"
"of the lyre, lyric poetry"
"old town, settlement"
"dweller by the cliff ford"
"victorious protection (Sigmund root)"
"Moorish, dark-skinned"
Similar sound: These names share phonetic patterns with Sidney — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Anglo-Norman French origins, giving them the same cultural heritage as Sidney.
Rhythm: Sidney is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.