Broderick sits next to 4 phonetic neighbors — Brodrick, Roderick, and Brock are the closest matches by sound. Most share Broderick's Welsh cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"son of Roderick"
"Great, magnificent, venerable"
"named after the Parisii Gallic tribe"
"bold, brave, daring"
"rock, harbor"
"halls, rooms"
"rain, precipitation"
"cold, enduring"
"valley"
"male deer, strong young man"
"unity, excellence, number one"
"narrow strait, slender (via Kyle)"
"selected, set apart"
"little fire"
"of Jove (Jupiter), sky father"
"noble spear (Edgar-derived)"
"dark one"
"little fiery one"
"help, strength"
"sadness, melancholy"
"star"
Similar sound: These names share phonetic patterns with Broderick — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Welsh origins, giving them the same cultural heritage as Broderick.
Rhythm: Broderick is a 3-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.