She brewed a year-and-a-day potion for her ugly son Morfran, but the boy Gwion Bach licked three drops by accident and gained all wisdom — fleeing through shape-shifts until he was swallowed by Ceridwen and reborn as Taliesin, the greatest bard in Welsh tradition.
Ceridwen does not currently appear in the US Social Security Administration's top 1,000 girls' names, so we don't publish a US rank or birth count for it. That says nothing about the name's standing elsewhere in the world — only that it sits outside the ranked US data we rely on.
In Pythagorean numerology the letters of Ceridwen reduce to 9, The Giver. This is a traditional interpretive system, not a factual claim about the name.