Livy writes:

　　We are expecting our second child, a daughter, in four weeks and we are completely stumped on girl names. We already have a son called Rex and his name was really the only one we could agree on but we both loved it; it fitted instantly. This time we have a lot of names that we both like but nothing that is ‘the one’.

　　We really want a name for our daughter that is strong, feminine, and not too frilly and, ideally, has the potential for nicknames. We are looking outside the top 100 names (we are in the UK so on the UK list) and want it to be interesting rather than popular or faddy.

　　Names we have on our shortlist are:

　　Adeline – Love Addie, but worry it will become popular.

　　Zosia – I love the Z, but my husband isn’t so keen.

　　Fable – My husband loves Fay and I love Fable so it should work but something isn’t quite right.

　　Juno – This was the initial frontrunner but it has sort of lost its shine. I am also not keen on June as a short form and can’t think of any logical others.

　　Xanthe – This shares the ‘x’ with her brother’s name but again, not quite right and no cute nicknames!

　　I love the nicknames Dora, Fin and Toby for a girl but would like a more formal, longer version as the official name and my partner has vetoed all of the long ones I can think of!

　　The Name Sage replies:

　　It’s easy to make long lists of baby names we like in theory. It’s a little harder to shorten those lists. But narrowing it down to just The Name, especially when the baby is due soon? That’s where it gets tough!

　　You’ve mentioned that you’d prefer to avoid frilly names. Some of the names on your list have a modern sensibility, like Xanthe and Zosia. Others feel more gently vintage, like Adeline and Dora.

　　The challenge is that both styles work beautifully with your son’s name, the handsome, regal Rex.

　　Let’s take a look at some names that are just a little bit different than the ones you’re currently considering:

　　Juniper – Juno leapt out at me immediately, and then I remembered that Coldplay’s drummer, Will Champion, has twins named Rex and Juno. You’ve mentioned that you’re not wild about shortening Juno to June. What if Juno was the nickname? Nature name Juniper is a longer Jun– option, one that is seldom heard in England. British Baby Names covered Juniper a few years ago, and noted that it has some connection to Cornwall.

　　Delphine – Another nature name, this time related to the flower delphinium. (Though the girls’ name and the botanical one both ultimately come from the Greek city of Delphi.) Delphine comes to mind because it might short to Fin – or Del/Dell, or Della, all of which seem like possible sister names for Rex. Along the same lines, I wonder if Josephine could shorten to Fin? It’s a stretch, but I think it could work.

　　Juliet – Julia is still fairly common in England, but Juliet seems quite rare. I added it to the list because of unconventional nickname possibility Jet. It seems as bold as Fable or Juno, but with slightly more history as a girl’s name. Jet is used as a nickname for ends-in-ette names in Dutch.

　　Dorothy, Theodora – Dory makes me think of Dorothy and Theodora, but I wonder if your husband has already scratched these off the list? I’m a huge fan of Theodora, which could easily shorten to Thea or Thora. The only trouble is that I think Thea is trending upwards in the UK, and might be slightly more popular than you’d like in a few years.

　　Constance, Colette, Cosima, or some other Co- name, called Coco – Juno always makes me think of Coco, a name that feels more like a nickname than a given name. Cosima strikes me as too frilly for your style, but Constance and Colette could work.

　　Adair – I think you’re right to keep an eye on all of the Addie names. Madeline/Madeleine has made a mark in the UK, so while the Ad– forms appear rare, it’s easy to imagine them catching on. Still, they’re not popular yet, and an unconventional Ad– name might be just the thing. Adair, originally a surname related to Edgar, feels bold, tailored, and very wearable. For a more vintage direction, there’s Adelaide or even the spare Adele.

　　Axelle, Beatrix, Roxana – There’s something appealing about another X name to go with Rex, but the choices are limited. Beatrix seems a little more traditional than the rest of your list, but it does pair beautifully with Rex, plus shortens to Bebe or Trixie or Tris. Axelle is very rare, and Roxana perhaps a bit too close. Still, matching Rex’s x is definitely worth considering.

　　Zora, Zara – If not another X name, maybe something starting with Z? You’ve mentioned that your husband isn’t sold on Zosia. Could one of the more streamlined Z names for girls appeal? Zora and Zara have different roots, but similar sounds.

　　My personal favorite is Adair. I think it hits all the marks – tailored, rare, with a built-in nickname. Adair strikes me as quite interesting and definitely outside of trends.

　　The other two that seem like great matches for Rex are Constance, called Coco, and Delphine, called Fin. Constance is such a strong, classic name, and while it’s steadily used in the UK, it’s not common, and doesn’t seem to be catching on. While Delphine called Fin is a stretch, I do think that Delphine is a gorgeous, underused name that hits the right note between strength and femininity.

　　What would you name a sister for Rex? UK readers, I’d be especially grateful for your insight!