Bly
A surname most likely meaning “son of Ely/Elie,” though it may also be a reduced form of a place-based name.
The #6,955 most common surname in the United States (2010 Census) — about 1 in every 64,015 Americans shares it.
Etymology
The best historical clue points to Bly as a shortened or altered form of Ely or Elie, used as a personal name in medieval records. In that reading, the surname would mean “descendant of Ely,” with Ely ultimately going back to the biblical Hebrew name Elijah via Latin and Old French forms. A place-name origin is also possible, but the excerpted sources favor the patronymic explanation.
History
Bardsley notes medieval examples such as "John fil. Elie," showing that Ely/Elie-style forms were in circulation as personal names from an early date. The surname Bly is comparatively uncommon today, and the historical evidence suggests it survived as a reduced spelling alongside other surname forms from the same name-base.
Origin
Regions
Variant spellings
Fun fact
The same medieval name-base could generate several modern surnames, so Bly, Ely, and Elie can sometimes sit in the same family-name orbit without being identical in every case.
From the historical record
“Introduction to Vol. I. It is necessary to say here that I do not agree with some of the statements made by Skeat in his paper, nota- bly the assertion that certain Egel- or .^Egel names are ' intermediate forms" or "later variants" of .iEthel- names: the two elements are quite distinct, although there may have…”
— Surnames of the United Kingdom: a concise etymological dictionary (2 vols in 1)