Let's go chronologically, beginning with the eldest of the cousins: Mason Dash Disick.
Kourtney and Scott Disick's oldest son was born Dec. 14, 2009, and the first-time parents put some serious thought into naming their baby boy.
"The first time I started looking at baby names, Mason was the only one I liked," Kourtney told Life & Style (via MTV News) back in 2010. "It was the only one that stuck with me. Right before he was born, I told my aunt we were thinking about going with that for a name. She told me that Mason means the same thing in English that Kardashian means in Armenian—stone worker. Another aunt told me my great uncle used to use the name Mason when he made dinner reservations, because Kardashian was too long. When I heard that, I thought, Oh my god, it's meant to be."
As for Mason's middle name? "Dash is not for my clothing store, as some people have suggested online," said Kourtney. "That would be stupid. Dash is short for Kardashian, and it was my father's nickname."
Penelope Scotland Disick, Kourtney and Scott's second child and only daughter, was born July 8, 2012. So how did mom and dad decide what to call her? They simply thought the name Penelope was cute, Kris Jenner told E! News at the time.
As for the middle name of Scotland, it was actually Kris' mom who suggested it while Kourtney was pregnant, and both Kourtney and Scott really liked it.
North West, born to Kim and Kanye West on June 15, 2013, was the next Kardashian cousin to come along.
In an interview with British GQ at New York's Mercer Hotel, Kim explained how she and Kanye decided on the name North. "I remember this is actually where we decided, finally, on North as a name for our baby girl," she said. "It was a rumor in the press and we'd never really considered it seriously, at all, but Kanye and I were having lunch right over there at that table about a year ago and Pharrell came over to us and said 'Oh, my God, are you guys really going to call your daughter North? That is the best name.' I said 'No we're not, that's just a rumor."
"Then a little while later Anna Wintour came over and asked the same thing," Kim continued. "She told us 'North is a genius name.' Kanye and I looked at one another and just laughed. I guess at that point it sort of stuck."
Grandma Kris weighed in on the name later, telling The View, "I love the name North! I'm pro-North, absolutely." Kris went on to say, "The way [Kim] explained it to me was that North means highest power and she says that North is their highest point together."
Reign Aston Disick, Kourtney and Scott's youngest, was born Dec. 14, 2014 (he shares a birthday with big brother Mason). Kourtney explained the significance of baby RAD's name to People, saying, "I'm never certain [with names] until they're born...I actually had the name [Reign] on our list with Mason. Then with Penelope, I had it on the list but spelled R-A-I-N."
Kourt was convinced baby No. 3 was a "girl in the beginning," and she was already considering the name Rain once again. "Once I was found out I was having a boy, we just changed the spelling again," she told People.
And on Dec. 5, 2015, Kim and Kanye welcomed son Saint West. An insider told E! News that Saint was picked since it's akin to saying he is "a blessing," especially "because [Kim] had such a difficult pregnancy."
Something tells us that Saint, Reign, North, Penelope and Mason will all welcome their newest cousin, baby Dream, with open arms!
Congratulations again to the whole family.