Cullum
Usually an English surname from Culham, Oxfordshire, though in some cases it may reflect a reduced form of a Gaelic name.
The #7,508 most common surname in the United States (2010 Census) — about 1 in every 69,616 Americans shares it.
Etymology
The most common explanation is that Cullum is a variant of Culham, the Oxfordshire place-name, with the surname meaning someone who came from that place. Older surname books note that this is an English local name and explicitly reject a connection with Mac-Cullum in those cases. A secondary possibility mentioned in later scholarship is that some examples may have been influenced by the Gaelic saint-name Colomb or related Celtic forms.
History
The name appears in English records in forms such as Colham, Culhame, and Cullum, showing the usual looseness of medieval spelling. It is found especially in England, and it may have arisen independently in more than one line. Because similar-looking Gaelic surnames exist, some families with this spelling may have separate origins.
Origin
Regions
Variant spellings
Fun fact
One nineteenth-century surname dictionary specifically warns that the English Culham-based name has nothing to do with Mac-Cullum.
From the historical record
“MAC CULLEN (Celt.) Son of Cullen, q.v. MAC CULLUM for Mao Galium, q.v. (Celt.) Son of Reavy, q.v.”
— Surnames of the United Kingdom: a concise etymological dictionary (2 vols in 1)