Niamh comes from the Old Irish niam, meaning "brightness" or "lustre." In Irish mythology, Niamh of the Golden Hair (Niamh Chinn Óir) was a princess of Tír na nÓg, the Land of the Young, who fell in love with the warrior-poet Oisín and brought him with her across the sea on a white horse.
Niamh is among the most common girl names in Ireland and is gaining ground in the wider Anglosphere. The one-syllable pronunciation (NEEV) catches outsiders off guard but is simple once known.
Niamh 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 Niamh reduce to 9, The Giver. This is a traditional interpretive system, not a factual claim about the name.