Lucus sits next to 4 phonetic neighbors — Lucas, Lukas, and Luke are the closest matches by sound. Most share Lucus's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"light, illumination"
"from Kelso (place name)"
"descendant of the peaceful one"
"noble lineage (adal) and eager (funs)"
"from the hare's den"
"keeper of the court"
"wisdom, scientific wonder (modern cultural meaning)"
"beloved of Yahweh"
"dwellers by the river forest"
"from the Roman city of Lindum"
"coal settlement; dark farmstead"
"manly beauty, sun god"
"warrior's town"
"modern American coinage"
"the great beast, tiger"
"handsome, beautiful"
"of the river (if -von is from Welsh afon)"
"compound Biblical name"
"wide island"
"handsome, well-born"
"dweller at the white cultivated land"
Similar sound: These names share phonetic patterns with Lucus — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Latin lux origins, giving them the same cultural heritage as Lucus.
Rhythm: Lucus is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.