Quincy is from the Old French — from the Latin quintus (fifth) — referring to the fifth-born child or a place name in France. Quincy Adams — Adams Family musical reference. Quincy M.E. Quincy Promes — Dutch footballer.
Quincy 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 Quincy reduce to 8, The Visionary. This is a traditional interpretive system, not a factual claim about the name.