Credit: Jon Kopaloff/FilmMagic

Suri, Apple, Monroe...and now Harper Seven!

On Sunday, Victoria Beckham gave birth to her first daughter, and she and husband David anointed their little one with a curious new moniker: Harper Seven!

So, what's in that name, anyway?

"Harper is an old english name that [Victoria] has always liked," a source close to Victoria, 37, and David, 36, tells Us Weekly.

(The Beckhams' little girl isn't the first Harper in Hollywood: Tiffani Thiessen and husband Brady Smith named their daughter Harper Renn after her June 2010 birth.)

But what about that "seven"? Although the number corresponds to soccer star David's old jersey number, the source explains: "Seven is a very spiritual lucky number. She was born in the seventh month, in the seventh hour."

The little girl arrived Sunday at 7:55 a.m. at Cedars-Sinai Hospital in L.A. Her older brothers are Brooklyn, 12, Romeo, 8, and Cruz, 6.