The "Black Widow" star joked that her husband Colin Jost's mother was not a huge fan of their decision to name their son Cosmo after she tried to suggest different names for the newborn.
While appearing on "The Kelly Clarkson Show," Johansson explained that her mother-in-law had a "harder time" with the baby's moniker while revealing the inspiration for the decision.
"We threw a bunch of letters together," she joked before elaborating. "I just thought it was charming and then our friends all liked it and then Colin's mom had a little bit of a harder time with it."
"She was like it just seems kind of…" the 37-year-old gestured with her hands. "It wasn't sitting [right] she kept suggesting other versions of it for a while and I was like 'no he's already like here. He's out, it's past that time.'"
Host Kelly Clarkson disagreed with Jost's mother and gushed about Cosmo's name. "I love that though, because your daughter is Rose," the former "Voice" coach referred to Johansson's daughter from her previous marriage. "I love that they’re both flowers! My kids hate plants and how much I love them… but I love flowers and plants and I thought that was kind of cool!"
"Not a lot of people make that connection, Cosmo is like a really sweet little flower [that] comes in different shades of orange and yellow and stuff like that. That's why my daughter liked it too," Scarlett replied.
Jost and Johansson first met when she hosted "Saturday Night Live" back in 2006, and they would see each other periodically over the years. It was when she came back for a cameo appearance during the 2017 finale as Ivanka Trump that the stars finally aligned.
The two got engaged in May 2019 and tied the knot in October 2020.
In August, Jost confirmed in an Instagram post that he and Johansson had welcomed their first child, writing, "Ok ok we had a baby. His name is Cosmo. We love him very much. Privacy would be greatly appreciated." However, it's unclear exactly when Johansson gave birth.
Cosmo is the first child for the couple, while Johansson also shares 7-year-old Rose with ex-husband Romain Dauriac.