One of Archie's first words had a special connection to Princess Diana.

Prince Harry shared the story about his son in his new docuseries The Me You Can't See, which premiered on Thursday night. It was a bittersweet memory for the Duke, who lost his mother when he was just 12 years old.

Prince Harry: Archie's first word for Princess Diana

Prince Harry revealed that his late mother Princess Diana has a special place in Archie's life — and she was actually one of his first words.

He explained: "I got a photo of her in his nursery, and it was one of the first words that he said. Apart from 'mama,' 'papa,' it was then 'grandma' — Grandma Diana."

Harry added, "It's the sweetest thing, but at the same time, it makes me really sad because she should be here."

Diana died tragically in a car crash in 1997, a time when Prince Harry was just a child. As a result, the Princess of Wales sadly didn't live to meet her grandchildren or see her sons become fathers.

Prince Harry speaks out on Princess Diana's death

The premiere of The Me You Can't See on Thursday also coincided with the release of a report on the BBC's unethical practices surrounding Princess Diana's 1995 Panorama interview.

Responding to the report, Harry called his late mother "an incredible woman who dedicated her life to service." He also blamed unethical journalism for Diana's death, saying, "Our mother lost her life because of this, and nothing has changed."

It is heartbreaking that Archie won't get to meet his grandmother, but he's already learning about the woman who meant so much to so many people.

Archie's First Words Broke Prince Harry's Heart

The 2-year-old Archie will also become a big brother in coming weeks, as Meghan is expecting a daughter this summer. The baby news has led many to wonder if the Duke and Duchess will honour Diana in some way in their daughter's name.

We now also know another of Archie's first words. In his recent interview with James Corden, Prince Harry had also shared that Archie's very first word was "crocodile."