Grimes and Elon Musk's son's name is officially on birth certificate

New parents Grimes and Elon Musk have officially listed their son’s name as X Æ A-XII Musk on his birth certificate.

The 32-year-old singer and the Tesla CEO welcomed their baby boy on May 4, naming him X Æ A-12 but later tweaking the moniker to comply with local law.

In a copy of the one-month-old’s birth certificate obtained by TMZ, it appears Grimes and Elon have settled on the name X Æ A-XII, replacing the numeral ‘12’ with the equivalent Roman numerals ‘XII’.

The document lists X as the boy’s first name, whilst Æ A-XII is his middle name and Musk is his surname.

The change to the spelling of X Æ A-XII’s name comes after Grimes recently confirmed they had to make the alteration in order to comply with California law, which doesn't permit Indo-Arabic numerals to be used in names.

Grimes — born Claire Elise Boucher — spoke about the change after an Instagram follower asked: “Did you change the baby name because of Californian laws? What is the baby's new name? (sic)”

And she replied: “X Æ A-Xii (sic)”

The Canadian music star subsequently added: “Roman numerals. Looks better tbh (sic)”

The unusual moniker has also sparked debate over the pronunciation prompting dad Elon to break down each element of his son’s name.

“It's just the letter X and then the Æ is pronounced 'Ash. A-12 is my contribution... Coolest plane ever. It's pretty great,” he said.

He also explained that Grimes “mostly came up with the name,” adding: “Yeah, she's great at names.”

And the SpaceX founder even corrected his partner’s explanation of their son’s name after she took to Twitter to explain its origins.

She wrote: “X, the unknown variable ... Æ, my elven spelling of Ai (love &/or Artificial intelligence) ... A-12 = precursor to SR-17 (our favourite aircraft). No weapons, no defences, just speed. Great in battle, but non-violent + (A=Archangel, my favourite song) (metal rat) (sic).”

However, Musk couldn’t help jumping into the comments to correct her reference to the aircraft, writing “SR-71, but yes.”

It didn’t take Grimes long to put him in his place, tweeting: “I am recovering from surgery and barely alive so may my typos b forgiven but, damnit. That was meant to be profound (sic).”

Elon quickly backed down and wrote: “You are a powerful [fairy emoji, queen emoji].”

Additional reporting by BANG Showbiz.

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