The name of an important ancient Roman emperor, Tiberius might sound a bit heavy for a modern boy to carry, but with the rise of Atticus, Tiberius and brothers begin to feel more baby-friendly, much in the same way as Old Testament names like Elijah and Isaiah have been rejuvenated.

Tiberinus was the god of the Tiber in Roman mythology and appears as a character in Virgil's Aeneid. It's related to the name Tiberius, that of an Ancient Roman emperor. Tiberius may be the better choice between the two, if only because it's more familiar.

Feminine form of Tiberius. It was used for women in ancient Rome, but not at all (yet?) by modern English speakers.