Christina, a pretty and feminine, crystal clear classic, may be trending downward, but it's never out of style. Christina's short forms Chris, Christie, and Tina all seem dated—making the royal Christina best used in its full glory.

Antonia is stronger than most feminized boys’ names, reflecting the pioneer spirit of Willa Cather's classic novel My Antonia. Antonia is hovering near the bottom of the US popularity list, which may be an excellent reason for you to use it.

Lost in limbo for decades and decades, Elsa now stands a good chance of following along in the progression from Emma to Ella to Etta, thanks to the ice queen heroine who "Let It Go" in the wildly popular Disney movie Frozen. The name shot all the up to Number 286 (its highest ranking since the 1890s) in the year after the release of the movie, though it's now dropped back down the list in the US.

Elva is a multicultural choice, being both an anglicization of the Irish Ailbhe and an feminine form of the name Alf, meaning "elf". Popular in the US at the beginning of the 20th century, it remained in the charts until the 1970s before falling out of favor.

A crystalline name that retains its loveliness far past its prime. Its biggest downside: Eternal confusion over spelling and pronunciation. Kristen? Kirsten? It can be so confusing that many parents today opt to bypass it.

Sigrid is a distinctly Scandinavian name that is starting to edge out into the wider world, a la cousin Ingrid. Unfortunately, short form Siri is now off the table, but Sigrid is still a possibility.

Romantic, and classy, this variation heats up Caroline and modernizes Carol, adding a southern accent. A popular choice in Portugal, Spain, Mexico, and Italy, it recently entered the US Top 500.

Lilly may contain one L too many for some people, though this secondary spelling of a name that's become wildly popular is still a popular choice. And the Lilly spelling does feel a bit less wispy, a bit more like a name as opposed to a mere flower, than the slender and delicate Lily. Lilly suggests the long-form Lillian, but it doesn't need to be an abbreviation for anything; Lilly can stand on its own.

A saint's name with a noteworthy literary background, including uses by Shakespeare in Two Gentlemen of Verona and Much Ado About Nothing, by Ben Johnson, Walter Scott, Longfellow, D. H. Lawrence and Neil Gaiman. In real life, her two most well known representatives are writer Ursula Le Guin and actress Ursula Andress. In literature, there is also Ursula Iguaran, a key, long-lived character in Gabriel Garcia Marquez's major work, One Hundred Years of Solitude.

A feminine form of Martin, this strong and zestful sounding name is popular in Argentina, Chile, Spain, and Italy, where it ranks in the Top 30. Also familiar in Czechia, the UK, Slovakia, and Switzerland, it has never made it big in the US, and fell out of the charts back in the 2000s.

Ultimately associated with Mars, the Roman god of war and with the 3rd century patron saint of Rome, it has also been borne by two notable tennis players, Martina Navratilova and Martina Hingis.

Rika is most common as a Japanese name, when it means "beautiful village" in one kanji combination. It is also seen as a nickname and given name in Scandinavia, Lithuania, and the Netherlands, where Rika originated as a nickname for names such as Fredrika and Henrika.

A popular name in the Middle Ages, Evelina was eclipsed by Evelyn in the last century, but has a chance at a well-deserved comeback now, fitting right in with the other Ev-names. Like Evelyn, it derives from the Norman name Aveline.

Matthias is the ancient Biblical form of Matthew, widely used along with brother Mathias in the US for the past 20 years.

Jasper and its many international variations, from Kasper to Casper to Gaspard, is finding new popularity.

Thora, related to Thor, is the ancient Norse thunder goddess name that's much softer and gentler than its meaning suggests. A noted bearer is actress Thora Birch.

Manly almost to the point of macho.

Sander is a more conventional form of Zander or Xander, heard frequently on its own in Europe. It is now a Top 20 name in Norway, and is also popular in Denmark, Belgium and the Netherlands. 

Carina is a pretty delicately feminine name whose fall from popularity is not helped by its similarity to hurricane name Katrina or slang victim Karen.

Whether you pronounce it my-a, ma-zha or ma-ha, Maja is an intriguing choice. Sometimes associated with Goya's famous painting "The Naked Maja." As a cognate of Maya, it's a Top 10 name in Slovenia and Sweden and is also popular in Germany and Norway.

Tove is a modern variation of an Old Norse name, related to Thor. Tuva is a form of the name popular in modern Scandinavia.