Elon Musk and Grimes have revealed what they actually call their son X Æ A-Xii.
After unveiling their baby's name, their fans were left baffled over how to pronounce it.
The couple had originally announced their baby was called X Æ A-12, but switched the numbers out for Roman numerals after California law meant they couldn't legally use the name, as numbers are not allowed.
Even with the change, it remained a bit of a mouthful.
But singer Grimes, 32, has shared the cute nickname they have for their son, "Little X", during a recent interview with Bloomberg .
Grimes, whose real name is Claire Boucher, welcomed her son with technology entrepreneur and SpaceX founder Elon, 48, on May 4.
Elon unveiled the name on Twitter after a fan asked what they'd chosen.
One fan then guessed the name was pronounced "X Ash Archangel", and Elon appeared to confirm it by liking the tweet.
But Grimes later explained the name on her own Twitter account.
She wrote: "X, the unknown variable.
"Æ, my elven spelling of Ai (love &/or Artificial intelligence)."
She then explained that the name has two meanings for her and Elon.
She posted: "A-12 = precursor to SR-17 (our favorite aircraft). No weapons, no defenses, just speed. Great in battle, but non-violent.
"A=Archangel, my favorite song."
After switching up the name to include Roman numerals, one fan asked Grimes: "Did you change the baby name because of Californian laws ? What is the baby's new name?"
She answered: "X Æ A-Xii", adding "Roman numerals. Looks better tbh."
She went on: "One dash is allowed."
Elon and Grimes started dating in 2018 and little X Æ A-Xii is their first child together.
Elon was already a dad to five children, twins Griffin and Xavier, and triplets Damien, Saxon and Kai. He also tragically lost a son called Nevada to Sudden Infant Death Syndrome.
