Sedna is the Inuit goddess of the sea and marine animals — one of the most important deities in Inuit mythology. The dwarf planet Sedna (discovered 2003) was named for her.
Sedna is rare but rising as Indigenous Arctic names gain wider recognition.
Sedna 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 Sedna reduce to 7, The Seeker. This is a traditional interpretive system, not a factual claim about the name.