Saoirse is the Irish word for "freedom" or "liberty" — a noun that became a given name only in the twentieth century, after Irish independence in 1922. It was associated with Republican politics for decades, and only became widely used as a name from the 1980s onward.
The pronunciation — roughly SEER-shah, though Irish speakers will note nuances no English transliteration captures — has been the chief obstacle to its spread outside Ireland. That changed when the actress Saoirse Ronan rose to fame in the late 2000s and quietly normalised the name in English-speaking countries. It is now one of the fastest-rising names in both the U.S. and the U.K.
Saoirse carries political weight in Ireland that it does not carry elsewhere — a freedom won, defended, named — but the meaning translates without losing its force.
Saoirse reduces to seven in Pythagorean numerology — the number of independence, introspection, and quiet conviction. A fitting number for a name meaning freedom.