Buachaillí

The name of the longest river in the British Isles rose to the US Top 25 for girls in the 1970s and the Top 100 for boys, but has fallen off the Top 1000 for both genders. At the latest count, the name Shannon was given to about 200 babies in the US, about a third of those boys. As a favorite Irish name, Shannon has now been supplanted by newcomers such as Saoirse and Seanan.

Actress Jaime King gave her son Leo the middle name Thames, for the famous London river where she and her husband Kyle Newman were married. Thames is pronounced tehms, not necessarily common knowledge in the US. The etymology of the word Thames is uncertain, and may mean dark but more likely stems from an ancient word for river.

As unlikely as it may seem, Theodore is a hot new hit name, vaulting into the Top 10 in 2021 for the first time ever. Friendly nickname Theo may be responsible for some of that, though there are plenty of baby boys given Theo as their full name too. Add their numbers together, and the two names jump to Number 6.