Nithya sits next to 3 phonetic neighbors — Niya, Nidhi, and Priya are the closest matches by sound. Most share Nithya's Indian-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"eternal, everlasting"
"determination, firm resolve"
"new, fresh, praiseworthy"
"arc, curve, arch"
"imperishable, eternal"
"power of the mind, brilliance"
"celestial being"
"charming woman"
"rocky hill, sacred high place"
"forest, woodland"
"air, wind, breath of life"
"to be revered, esteemed"
"the dark one"
"radiance of a gem or celestial body"
"luck, fortune"
"built, son of (biblical)"
"grace, ornament"
Similar sound: These names share phonetic patterns with Nithya — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Sanskrit origins, giving them the same cultural heritage as Nithya.
Rhythm: Nithya is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.