Cecylia is from the Polish Cecylia — from Latin Caecilia — from Latin caecus (blind). Cecylia is one of the Polish feminine names — central to traditional Polish Catholic + European heritage. 2nd-3rd c. Cecilia's Day (1739) Benjamin Britten's Hymn to St.
Cecylia 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.
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In Pythagorean numerology the letters of Cecylia reduce to 4, The Builder. This is a traditional interpretive system, not a factual claim about the name.