Whitney comes from the English surname meaning "white island" — from Old English hwit (white) and eg (island). Whitney Houston (1963-2012) gave the name international visibility.
Whitney peaked at #40 in the U.S. in 1985. Today it sits outside the top 1000 but is quietly used — a 1980s classic awaiting revival.
Whitney 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 Whitney reduce to 5, The Seeker. This is a traditional interpretive system, not a factual claim about the name.