Thelonious sits next to 4 phonetic neighbors — Cornelius, Aurelius, and Cassius are the closest matches by sound. Most share Thelonious's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"lord, ruler"
"sword (card suit origin)"
"world ruler"
"whole, universal"
"cheerful, merry"
"Filipino presidential surname name"
"stone sword, sword stone"
"tournament fighter, gladiator"
"with excellent melody"
"noble friend"
"hare's meadow, woodland clearing"
"slender, narrow"
"precious, greatly valued thing"
"victorious one"
"one who protects"
"God is gracious (via Sean)"
"invented modern variant"
"son of Daw (David), beloved son"
"wreath of flowers, festive crown"
"broad, wide"
"mythical fire bird of rebirth"
Similar sound: These names share phonetic patterns with Thelonious — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Germanic/Latin origins, giving them the same cultural heritage as Thelonious.
Rhythm: Thelonious is a 4-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.