Thedra sits next to 4 phonetic neighbors — Thedra, Thea, and Phedra are the closest matches by sound. Most share Thedra's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"gift of God"
"blooming, goddess of flowers"
"joy, happiness"
"clergy, learned one, one who casts lots"
"forest spirit"
"bold, to have courage"
"peaceful ruler (from Frederika)"
"yew tree"
"flowering, in bloom"
"spring-born, of the spring season"
"merriment, joyful laughter"
"God is gracious"
Similar sound: These names share phonetic patterns with Thedra — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Greek origins, giving them the same cultural heritage as Thedra.
Rhythm: Thedra is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.