Treasa is from the Irish Treasa — strong, mighty also Irish form of Teresa / Theresa from Greek therizein (to harvest). Treasa is one of the Irish feminine names — central to traditional Irish Catholic heritage. Irish feminine name reflecting Catholic heritage.
Treasa 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 Treasa reduce to 1, The Leader. This is a traditional interpretive system, not a factual claim about the name.