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Elon Musk and Grimes’ baby girl name will make you say, ‘Y?’

The Canadian singer and the Tesla CEO are also parents to X.
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Surprise! Elon Musk and Grimes have welcomed baby number two.Kevin Tachman / Getty Images for Vogue
/ Source: TODAY

The unusual baby girl name chosen by Grimes and Elon Musk has been revealed: Exa Dark Sideræl Musk, also known as "Y."

Grimes shared in the April cover story of Vanity Fair she and Musk welcomed their second child, a girl, with the help of a surrogate in December 2021.

What did Elon Musk and Grimes name their daughter?

According to Vanity Fair, Grimes, 33, and the SpaceX founder and Tesla CEO, 50, call their newborn daughter “Y,” though her full name has a complex meaning.

If the name sounds like something from a different space and time, that’s because it is.

Related: Grimes says baby doesn’t call her ‘Mom’ — and instead calls her this

Exa Dark Sideræl Musk

Starting at the beginning, Exa is "a reference to the supercomputing term exaFLOPS (the ability to perform 1 quintillion floating-point operations per second)."

Dark is representative of “the unknown. People fear it but truly it’s the absence of photons. Dark matter is the beautiful mystery of our universe.”

And Sideræl is both a special nod to Grimes' favorite "Lord of the Rings" character, Galadriel, as well as an "elven" spelling of sidereal, or "the true time of the universe, star time, deep space time, not our relative earth time.”

How do you pronounce Sideræl?

Grimes shared with Vanity Fair the correct phonetic pronunciation of her daughter's name — Exa Dark Sideræl Musk — is “sigh-deer-ee-el”.

The mom of two, whose name at birth was Claire Elise Boucher, told the outlet she would support her daughter changing her name in the future, even adding she worries Exa Dark Sideræl is “a little boring.”

“I was fighting for Odysseus Musk,” she writes. “A girl named Odysseus is my dream.”

The couple are also parents to 22-month-old X Æ A-12, which is pronounced “X Ash A Twelve.”

“First of all, my partner’s the one that mostly came up with the name,” Musk told “The Joe Rogan Experience” podcast in 2020. “It’s just X, the letter X, and then the ‘Æ’ is pronounced, ‘Ash,’ and then, ‘A-12’ is my contribution.”

Y is the eighth child for Musk, who has six sons from a previous marriage. In 2002, Musk lost infant son Nevada at 10 weeks.

“My firstborn son died in my arms," Musk wrote in an email exchange reported by Business Insider earlier this year. "I felt his heartbeat.”