Esyllt is the Welsh form of Iseult (Isolde) — heroine of one of the great romantic tragedies of Western literature. The Irish princess who fell in tragic love with the Cornish knight Trystan after they accidentally drank a magic potion — central to the Welsh Triads (which predate the French versions). Generally interpreted as meaning "of fair regard."
Featured in the Welsh Triads and medieval Welsh romance.
Esyllt 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 Esyllt reduce to 3, The Communicator. This is a traditional interpretive system, not a factual claim about the name.