Narcissa sits next to 4 phonetic neighbors — Narcissa, Marissa, and Larissa are the closest matches by sound. Most share Narcissa's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"narcissus flower, sleep-inducing"
"king"
"midsummer, summer solstice"
"washed, cleansed; or variant of Lavinia"
"horn, strength"
"Noble and famous"
"worthy of admiration"
"bright like a bear"
"variant of Cinda/Cindy"
"little light"
"gentle, mild"
"the white, noble one"
"variant of Chloris, goddess of flowers"
"prosperous friend"
"flowing, moving freely"
"settlement of the Britons"
Similar sound: These names share phonetic patterns with Narcissa — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Greek narkissos via Latin origins, giving them the same cultural heritage as Narcissa.
Rhythm: Narcissa is a 3-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.