Cydney sits next to 5 phonetic neighbors — Sydney, Sidney, and Cindy are the closest matches by sound. Most share Cydney's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"wide island"
"ivory-white, creamy white"
"chalk wharf, landing place on the Thames"
"musical conclusion or tail"
"salt water, brine"
"olive tree"
"Work-power; industrious leader"
"defender of mankind"
Similar sound: These names share phonetic patterns with Cydney — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Old English origins, giving them the same cultural heritage as Cydney.
Rhythm: Cydney is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.