Casey sits next to 3 phonetic neighbors — Kasey, Lacey, and Macy are the closest matches by sound. Most share Casey's Irish-rooted cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"dweller in the wild, untamed land"
"thankful, God has heard"
"Frankish person"
"administrator of justice"
"meadow dwelling, water meadow"
"battle"
"brave in battle"
"lion (leonem)"
"wealthy"
"dweller near the woods"
"from the castle, place near the ditch"
"frisky, energetic youth"
"fair, white, bright"
"from Grantham"
"good fortune, luck"
"beauty, grace, excellence"
"may God protect"
"cheerful, pleasant"
"mill worker, grain grinder"
"handsome"
Similar sound: These names share phonetic patterns with Casey — similar vowel sounds, consonant clusters, or rhythm.
Rhythm: Casey is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.