Douglas sits next to 4 phonetic neighbors — Dustin, Duncan, and Dallas are the closest matches by sound. Most share Douglas's Scottish cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"dark blue water"
"from Mauritania"
"slender and fair"
"powerful ruler of the home"
"vigor and power"
"roof maker"
"beloved companion"
"tile maker (short for Tyler)"
"remembered by Yahweh"
"dragon"
"son of Jack"
"western settlement"
"herb farm, meadow settlement"
"wood, forest"
"God-like"
"twin"
"gift of God"
"youthful, young one"
"father of light"
"powerful counselor (via Ronald)"
"open grassy land"
Similar sound: These names share phonetic patterns with Douglas — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Scottish Gaelic origins, giving them the same cultural heritage as Douglas.
Rhythm: Douglas is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.