Kai is an internationally flexible name with many possible origins and meanings, growing in popularity in the US and a diverse range of European countries.

Strong and modern, Cade shot up the popularity lists around the millennium—it was as high as Number 201 in 2001. Now, it has declined in popularity slightly, but nevertheless remains in the US Top 300, given to around 1200 babies each year. Combined with all the baby Kades, Cadens, Kaidens and Kaydens however, it might feel even more popular that it actually is.

The new Maia, the next Kayla, Kaia has been on the charts since the year 2000. You might see it as a female form of the also-rising Kai, which means sea in Hawaiian and is sometimes used for girls as well, or as a Kardashianization of the ancient goddess name Caia.

Catherine is one of the oldest and most consistently well-used girls’ names, with endless variations and nicknames. The Catherine form feels more gently old-fashioned and feminine than the more popular K versions. Most stylish nickname for Catherine right now: Kate...or Cate, a la Blanchett.

Katherine is one of the oldest, most diverse, and all-around best names: it's powerful, feminine, royal, saintly, classic, popular, and adaptable. Long one of the top girls' names starting with K, Katherine has now been unseated on the popularity list by upstarts Kennedy and Kinsley, but a dip in popularity only adds to its charm.

Kayla is a modern invented name that emerged in the late 1950s. It may have been inspired by the similar sounding Michaela, though it could equally have come about as a combination of the then popular name popular name Kay and the familiar -la suffix.

A name of multiple identities: a somewhat soap-operatic single-syllable surname, a homonym for the biblical bad boy Cain, and, when found in Japan and Hawaii, it transforms into the two syllable KA-neh. Kane also has multiple meanings: in Welsh, it's "beautiful"; in Japanese, "golden"; and in Hawaiian, "man of the Eastern sky."

Sweet and sunny but substantial too, Callie is a nickname-style choice that has long been used as a stand-alone option . Traditionally a diminutive of classic Caroline, it may also be used for Calliope, Camila, Callista, Calanthe, and beyond.

Cataleya is the name of a genus of orchids that gained visibility as a baby name after it was used for the character played by Zoe Saldana in Colombiana. Part Caitlin, part Aaliyah, and part Leah, Cataleya is a trendy choice that just might transcend its momentary popularity. It is a spelling adaptation of Cattleya, named after the British horticulturalist William Cattley.

Kathleen is the early Irish import version that came between Katherine and Kaitlin, and which hasn't been used in so long it's almost beginning to sound fresh again. It was a surprise pick by one of the hip Dixie Chicks, Martie Maguire. Kathleen was a Top 10 name from 1948 to 1951, and it is the subject of several old sentimental songs, such as "I'll Take You Home Again, Kathleen."

Friendly mega-popular short form of Katherine that has definitively replaced Kathy, Katie is often given on its own. Going forward, though, Katie is more stylishly clipped itself to the grownup Kate.

Popular pop name, inspired by Australian singer Kylie Minogue. It was at its height in Australia in the 1970s and early 80s; often cited as a Noongar name meaning "boomerang".

Caden is a key member of the rhyming contingent that includes Aiden, Jayden, Kayden, Brayden et al. It may derive from the Celtic Cadan or Irish Cathán, both from the same root meaning "battle". It is also possible it comes from Cade, meaning "round" or "barrel".

Kiki is one of the Coco-Gigi-Fifi-Lulu bohemian-type French nickname names from the turn of the last century, which have endless energy and sparkle. Artist Kiki Smith is its most well-known contemporary representative, and Kiki was the inspiring heroine of Zadie Smith's On Beauty. Kiki can be a nickname for any name beginning with the K sound, from Katherine to Christina to Kayla.

A popular member of the -ayden family, Kaden ranks alongside Kaiden, Kayden, Kasen, Kade, Caiden, Cade, and Caden in the US Top 1000. A 90s invention that took off in the 2000s, Kaden is concise and modern, with its popular K initial.

This endearing nickname name is one Katherine pet form that predates all the Kathys and Katies, having been fairly common in the eighteenth century. With the current mini-craze for animal-related names, Kitty is sounding cute and cuddly again—she's already jumped back onto the U.K. list, at number 199.

This name of a touristed island in sight of Los Angeles makes an attractive and newly stylish variation on the classic Catherine or overused Caitlin.

Kali is a number of different things: a playful, contemporary twist on the name Callie; the Hindu goddess of destruction; an alternative spelling for Kaylee; a short form of the Arablic Kalila, the Greek Kalista, or the African American Kaliyah; a masculine name in India; and a trendy form of Kali(fornia).

This member of the aden/ayden extended family is a popular choice not only in the US but across the pond in England, Wales and Scotland as well. Angie Everhart has a son named Kayden Bobby.

Katerina and its near-identical twin Katarina have a pleasingly lilting European sound, though for some Americans they may be uncomfortably close to Katrina, which will be linked for a long time to the hurricane that devastated New Orleans.