Ancestry.com gives 5 possibilities for the name: Irish: Anglicized form of Gaelic Ó Colmáin ‘descendant of Colmán’. This was the name of an Irish missionary to Europe, generally known as St. Columban (c.540–615), who founded the monastery of Bobbio in northern Italy in 614. With his companion St. Gall, he enjoyed a considerable cult throughout central Europe, so that forms of his name were adopted as personal names in Italian (Columbano), French (Colombain), Czech (Kollman), and Hungarian (Kálmán). From all of these surnames are derived. In Irish and English, the name of this saint is identical with diminutives of the name of the 6th-century missionary known in English as St. Columba (521–97), who converted the Picts to Christianity, and who was known in Scandinavian languages as Kalman. Irish: Anglicized form of Gaelic Ó Clumháin ‘descendant of Clumhán’, a personal name from the diminutive of clúmh ‘down’, ‘feathers’. English: occupational name for a burner of charcoal or a gatherer of coal, Middle English coleman, from Old English col ‘(char)coal’ + mann ‘man’. English: occupational name for the servant of a man named Cole. Jewish (Ashkenazic): Americanized form of Kalman. Americanized form of German Kohlmann or Kuhlmann. I would say that the odds favour the first one, BUT, you would have to trace your family backwards to find out for sure. If you get back to your immigrant ancestor, you might be able to find his place of origin, which will give you a strong hint as to the origin of your name.

Cabbage farmers.