Hillary sits next to 4 phonetic neighbors — Hilary, Ellery, and Mallory are the closest matches by sound. Most share Hillary's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"cheerful, merry, joyful"
"the desired one"
"divine nature, godliness"
"wealthy"
"rich reddish-brown tropical hardwood"
"famous warrior"
"creative blend of Ja- prefix and Leah (weary)"
"coconut"
"my lady (title)"
"coal town, dark settlement"
"eternal flower, forever flowering"
"supplanter"
"from Tracé, Normandy"
"divine sky child"
"of the wood"
"brave as a lion"
"fine art, artistry"
"island of Kell, Kell's island"
"short form of Katarina"
"harmony, concord, agreement"
"gift of God's grace"
Similar sound: These names share phonetic patterns with Hillary — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Latin origins, giving them the same cultural heritage as Hillary.
Rhythm: Hillary is a 3-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.