Petra sits next to 4 phonetic neighbors — Pietra, Peta, and Beatrix are the closest matches by sound. Most share Petra's German-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"rock, stone"
"violent weather, tempest"
"wisdom"
"little Anne, dear Anne"
"consecrated to God"
"Our Lady of Mercies (Marian title)"
"hope"
"sky, atmosphere"
"defender of mankind"
"sea of bitterness (via Mary/Myra)"
"star of the sea"
"God is gracious"
"born at dawn"
"beloved, variant of Maria"
"pious, devout"
"angry, wrathful"
"goddess of spring, month of May"
"daughter of Jove, sky-father"
"sky blue, azure color"
"wool"
"other, foreign"
Similar sound: These names share phonetic patterns with Petra — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Greek origins, giving them the same cultural heritage as Petra.
Rhythm: Petra is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.