Merlin \m(e)-rlin, mer-lin\ as a boy's name is pronounced MER-lin. It is of Welsh origin, and the meaning of Merlin is "sea fortress". Mythology: Arthurian tales describe Merlin as the wizard who was King Arthur's mentor. Myrddin, the wizard who tutored King Arthur in British legend was known as Myrddin Emrys. Writers translated this into Latin as Merlin Ambrosius, and into English as Mervyn. It was a mistake as the first part of the name was a Welsh place name for the seacoast town of Carmarthen. Emrys was the personal name and a Welsh version of Ambrose. So Merlin probably means "Ambrose of Carmarthen", and is only vaguely related to Mervyn and its variants. Football player Merlin Olsen.