Allegra sits next to 4 phonetic neighbors — Alejandra, Alora, and Allegro are the closest matches by sound. Most share Allegra's Italian-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"joyful, lively"
"born at Christmas (Noelle variant)"
"industrious, hardworking"
"bright light"
"God is gracious"
"dolphin"
"my father is joy, father's joy"
"lake land"
"slender, fair maiden"
"grace, favor"
"deep valley dwellers"
"gift, God is salvation"
"broad island (alternative etymology)"
"that which has been firmly established"
"one who works the earth"
"free man"
"blessed, fair one"
"great, venerable"
"grace + belonging to God"
"crowned with laurels (via Stephanie)"
"from the surname Payson, New England Puritan heritage"
Similar sound: These names share phonetic patterns with Allegra — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Italian origins, giving them the same cultural heritage as Allegra.
Rhythm: Allegra is a 3-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.