Gillian sits next to 4 phonetic neighbors — Julian, Jillian, and Vivian are the closest matches by sound. Most share Gillian's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"youthful"
"variant of Kaylin (pure)"
"wry meadow"
"unintelligible speakers (Sioux term for Cheyenne people)"
"old age (Norse mythology personification)"
"pure, slender"
"solitary, unique"
"elm tree clearing"
"youthful, young"
"God is my oath"
"free woman, free man"
"beautiful, of light"
"queen, wealth"
"milk of sleep (plant property)"
"descendant of the courageous one"
"son of Finlay (fair-haired hero)"
"hidden one"
"war, combat"
"queen, wife of the khal"
"lily flower"
Similar sound: These names share phonetic patterns with Gillian — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Latin origins, giving them the same cultural heritage as Gillian.
Rhythm: Gillian is a 3-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.