Alethea sits next to 3 phonetic neighbors — Althea, Alethia, and Aletha are the closest matches by sound. Most share Alethea's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"truth"
"whole, universal power"
"noble kind (short form of Alice)"
"lily"
"sun, sunlight"
"resurrection, she who shall rise again"
"bright one, term of endearment"
"social gathering, party"
"golden ruler"
"hidden, possibly myrtle plant"
"beautiful, lovely"
"joy, happiness"
"supplanter"
"full of life and energy"
"delight, bliss"
"free spirit (modern connotation)"
"strong, manly (feminine adaptation)"
"joyful, my God is abundance"
"night, darkness"
"old friend"
"divine strength (from Osbourne)"
Similar sound: These names share phonetic patterns with Alethea — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Greek origins, giving them the same cultural heritage as Alethea.
Rhythm: Alethea is a 4-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.