Medea (Μήδεια) is from the Greek mēdomai, meaning "to plot" or "to scheme." The Colchian sorceress and granddaughter of the sun god Helios who helped Jason steal the Golden Fleece — and then, when he betrayed her, killed their children. Subject of Euripides's tragedy.
Medea is rare but iconic.
Medea 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 Medea reduce to 1, The Leader. This is a traditional interpretive system, not a factual claim about the name.