Thaddeus sits next to 4 phonetic neighbors — Theodore, Tobias, and Matthias are the closest matches by sound. Most share Thaddeus's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"courageous heart"
"son of the right hand"
"wild goat (ibex)"
"ruler, sovereign"
"spiritually reborn through baptism"
"olive tree"
"sea fortress, sea friend"
"raven"
"a narrow road or lane"
"farm settlement of Dudda"
"noble, handsome"
"well-born, of noble birth"
"visitor, pilgrim"
"Trent's town, settlement on the Trent"
"love and goodness"
"renowned warrior"
"poet, bard"
"my God is salvation"
"from Denmark, a Dane"
"mind, intellect, spirit"
Similar sound: These names share phonetic patterns with Thaddeus — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Aramaic origins, giving them the same cultural heritage as Thaddeus.
Rhythm: Thaddeus is a 3-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.