Jeffrey sits next to 4 phonetic neighbors — Geoffrey, Jeffery, and Jerry are the closest matches by sound. Most share Jeffrey's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"pledge of peace"
"from Antwerp"
"God has given"
"long narrow hill"
"free man"
"true, faithful"
"God's helper (ezer + El)"
"to follow a course, leave a mark"
"wolf lover"
"kingly"
"man from South Munster"
"good place"
"name of God"
"son of the blessed one"
"king, master"
"western clearing"
"from the island of Rhodes"
"counsel + wolf (rád + ulfr)"
"spear rule"
"narrow strait"
"increase, growth"
Similar sound: These names share phonetic patterns with Jeffrey — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Germanic origins, giving them the same cultural heritage as Jeffrey.
Rhythm: Jeffrey is a 3-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.