Sihu is a Hopi (Native American, Arizona) word for "flower." The Hopi people of the Arizona mesas have one of the most continuously inhabited regions in North America (over 1,000 years).
Sihu is rare but distinctive.
Sihu 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 Sihu reduce to 3, The Communicator. This is a traditional interpretive system, not a factual claim about the name.