Morgan Morgan's surname originates from Welsh. The definition is derived from the given name Morgan, from "mor", the sea, and "gan," born. Other spellings of Morgan are: Morgen, Morgain, and Morgaine. Other sites contained this information: “from Mor, the sea, and gan, born; the same as Pelagius--born on the sea, from the Greek, the sea. Mor, the sea, and gan, by or near--near the sea, a locality.” “Welsh: from the Old Welsh personal name Morcant, which is of uncertain but ancient etymology. Irish: importation of the Welsh surname, to which has been assimilated more than one Gaelic surname, notably Ó Muireagáin. Scottish: of uncertain origin; probably from a Gaelic personal name cognate with Welsh Morcant.”