Felicity comes from the Latin felicitas, meaning "happiness" or "good fortune." In Roman religion, Felicitas was the goddess of good fortune. Saint Felicity (2nd-3rd century) was an early Christian martyr.
Felicity entered the U.S. Today it sits in the U.S.
Felicity 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 Felicity reduce to 8, The Visionary. This is a traditional interpretive system, not a factual claim about the name.