Glenys is from the Welsh Glenys — holy, pure, blessed from Welsh glân (pure, holy). Glenys is one of the Welsh feminine names — central to traditional Welsh heritage. Welsh feminine name reflecting Celtic Indigenous heritage.
Glenys 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 Glenys reduce to 1, The Leader. This is a traditional interpretive system, not a factual claim about the name.