Baby in training! Grimes and Elon Musk's newborn X AE A-XII is apparently learning an interesting skill. The new mom posted a photo of her son wearing a T-shirt featuring a word you've probably never heard of before.

The Vancouver-born singer posted a snap on her Instagram story that shows a small glimpse of his face including his nose and mouth with his little tongue sticking out.

As for attire, the infant is wearing a black shirt with gold writing featuring the phrase "Mentat in Training."

According to Urban Dictionary, a mentat is "a literary reference from Frank Herbert's Dune series describing someone who has been extensively trained to emulate the mental calculating capacity of a computer."

"Mentats have a tendency to analyze everything as if it were data for a calculation. This term describes someone who over-analyzes every situation."

Grimes didn't offer any explanation for why she and Musk's son had that shirt on or what exactly the training entails.

The image was posted as part of a collection of photos on her story urging her followers to register to vote.

grimes | Instagram

The two-month-old was born on May 4 and has made a few appearances on his mom's Instagram stories, including an adorable video of him cuddling with his dad.

As you'll recall, he was originally born with the name X Æ A-12, but a series of name changes were necessary.

First, the parents had to ditch the numerals in order to comply with California laws, so he became X Æ A-Xii.

After that, an image of his birth certificate revealed that the Æ was a no-go. Now, his legal first name is X, middle name is AE A-XII, and he took Musk's last name.

The super-easy pronunciation is actually just said "X Ash A 12" but it seems like both parents enjoy calling him by nicknames.

Grimes shared that she says "Little X" and Musk revealed in a video that he calls his son "Baby X."