Sei is a boy name. It last appeared in U.S. Social Security records in 2007. Sei first appears in the data in 2007 and reached its peak in 2007 (7 births). The chart below shows how the name has risen and fallen over time.
How popular is Sei? (U.S. births per year)
U.S. births per year, 2007–2007 · hover or tap for the count and national rank · source: U.S. Social Security Administration