More unusual than Tessa, this would make an interesting, meaningful and attractive choice for a third child.

Tertia—which is occasionally used in the UK, but rarely in the US, would make an unconventional but interesting possibility for the third child in a family. Terza and Terzo are lively Italian female and male variations.

It's difficult to conceptualize the numerical value of a trillion, but this extraordinarily large number name is a rising choice for baby boys.

Amphitrite is a mysterious Greek mythological figure, most often cited as a sea goddess who was the wife of Poseidon. She was said to be the personification of the sea water itself and was said to be present at the birth of Apollo.

Strong and vital Asian birth order name.

Never as well known as that other Roman numeral name, Octavius, Tertius just might hold some appeal for the parent seeking a really obscure name with the patina of antiquity for her third son.

An interesting international possibility for a third son.

Pretty, zippy and almost unknown, this Italian name would suit a third child.