Lucille sits next to 3 phonetic neighbors — Lucy, Lucile, and Louise are the closest matches by sound. Most share Lucille's French-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"light, illumination"
"strong, healthy, from the Latin valere"
"the moon"
"banana plant"
"flag, banner"
"noble strength"
"divine grace, blessing"
"may God increase"
"free person"
"noble kind"
"ivory white"
"alive, lively"
"descendant of Leannán"
"of noble birth"
"of the Magdalene order"
"king of elves"
"son of Colin, victory of the people"
"noble, nobility"
"prayer"
"little ruler, impulsive one"
Similar sound: These names share phonetic patterns with Lucille — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Latin Lucia/Lux origins, giving them the same cultural heritage as Lucille.
Rhythm: Lucille is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.