Day sits next to 5 phonetic neighbors — Dae, Dei, and Ray are the closest matches by sound. Most share Day's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"daylight, the day"
"old, wise ruler"
"noble, nobility"
"raven"
"black and blue-green"
"glory of the homeland"
"pillar, column"
"eagle"
"sunray, shining light"
"The great; the large"
"alder tree dweller"
"from Flanders, Flemish person"
"flower settlement"
"olive tree; symbol of peace and wisdom"
"the strait, narrow waterway"
"stony forest"
Similar sound: These names share phonetic patterns with Day — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Old English origins, giving them the same cultural heritage as Day.
Rhythm: Day is a 1-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.