Washington - Singer-songwriter Grimes recently revealed that she has secretly welcomed a baby girl with Elon Musk in December 2021 via surrogate.
People Magazine obtained quotes of Grimes' cover story for Vanity Fair's April 2022 issue.
Grimes, 33, who is also mom to a 22-month-old son with the Tesla founder, 50 - shared the baby's full name is Exa Dark Siderael, though they've nicknamed her Y.
Grimes explained her daughter's unique name to the outlet, saying that Exa refers to a supercomputing term, exaFLOPS, while Dark represents "the unknown."
She explained, "People fear it but truly it's the absence of photons. Dark matter is the beautiful mystery of our universe."
Siderael, the third part of Y's full name, is pronounced "sigh-deer-ee-el". Grimes called the word "a more elven" spelling of sidereal, which she defined as "the true time of the universe, star time, deep space time, not our relative earth time."
Siderael has a double meaning, too, as a shout-out to Grimes' favourite ’Lord of the Rings’ character, Galadriel, who "chooses to abdicate the ring."
Grimes also shared that she was "fighting" to name her daughter Odysseus Musk, because "A girl named Odysseus is my dream," but she and Musk settled on Exa Dark Siderael instead.
Despite splitting up in September 2021 after three years together, Grimes and Musk are back together.
"There's no real word for it," she said. "I would probably refer to him as my boyfriend, but we're very fluid. We live in separate houses. We're best friends. We see each other all the time.... We just have our own thing going on, and I don't expect other people to understand it."
She added that she and Musk are happy together, telling the outlet, "This is the best it's ever been. ... We just need to be free."
She also shared that they plan to have more children too: "We've always wanted at least three or four."