Sydney is from the Old English place-name sid (wide) + eg (island) — or the French Saint-Denis. Sydney McLaughlin-Levrone (born 1999) — American hurdler; the world-record holder in the women's 400 metres hurdles, which she has broken six times (currently 50.37 seconds, set at the 2024 US Olympic Trials).
Sydney 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 Sydney reduce to 2, The Peacemaker. This is a traditional interpretive system, not a factual claim about the name.