Sydney sits next to 3 phonetic neighbors — Sidney, Sydni, and Cydney are the closest matches by sound. Most share Sydney's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"wide island"
"divine wonder"
"shade, silhouette"
"small fort"
"noble, virtuous"
"vivid, alive"
"modern invented name with phonetic appeal"
"authority, firm determination"
"battle settlement"
"combination of Jay + lyn suffix"
"worker in hard materials"
"city of art and history"
"skilled leader, one who knows (English surname origin)"
"healing, remedying"
"strict, disciplined"
"son of the sea, born from ocean waves"
"hollow"
"heather, heath plant"
"lover of churches, bright-headed"
"rye meadow"
"watchman, alert"
Similar sound: These names share phonetic patterns with Sydney — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Old English sid (wide) and eg (island) origins, giving them the same cultural heritage as Sydney.
Rhythm: Sydney is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.