Vaishnavi (वैष्णवी) is the Sanskrit word for a female devotee of Vishnu — also an epithet of Lakshmi, Vishnu's consort.
Vaishnavi is widely used across India.
Vaishnavi 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.
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In Pythagorean numerology the letters of Vaishnavi reduce to 6, The Nurturer. This is a traditional interpretive system, not a factual claim about the name.