Collie sits next to 4 phonetic neighbors — Callie, Mollie, and Holly are the closest matches by sound. Most share Collie's Scottish cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"coal black, dark-complexioned"
"diminutive term of endearment"
"Possibly a diminutive of Genoveva (noble woman) or variant of Janel..."
"little fortress, little stronghold"
"fortune, riches"
"well-spoken, eloquent"
"fair, smooth"
"Dorian woman, from the Dorian people"
"modern variant of Majella"
"truth"
"Wealth, honor"
"good; well; true"
"king"
Similar sound: These names share phonetic patterns with Collie — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Scottish Gaelic origins, giving them the same cultural heritage as Collie.
Rhythm: Collie is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.