Hi Savie,
I'll just quote the book "Celtic Baby Names" by
Judy Sierra, but you'd better wait until Merriment confirms (as there have been a couple of mistakes in that book already!):
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Iolo m. (YOH-loh) A common nickname for
Iorwerth, often used as a name in its own right.
Iolo Morganwg (
Iolo of Glamorgan) was the bardic name of
Edward Williams (1747-1826), stonemason, poet, scholar and initiator of the modern National Eisteddfod.
Iowerth m. (YOHR-wayrth) From Norse 'iôr' "lord" + Welsh 'gwerth' "value, worth". From the Middle Ages to the present,
Iorwerth has been use as a Welsh version of
Edward.
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Regards,
Satu