The name of the town changed several times over the centuries. The modern Greek name of the town is Nafplio (Ναύπλιο). In modern English, the most frequently used forms are Nauplia and Navplion.
During the Classical Antiquity, it was known as Nauplia (Ναυπλία) in Attic Greek and Naupliē (Ναυπλίη) in Ionian Greek. In Latin, it was called Nauplia.
During the Middle Ages, several variants were used in Byzantine Greek, including Náfplion (Ναύπλιον), Anáplion (Ἀνάπλιον), and Anáplia (Ἀνάπλια).
During the Late Middle Ages and early modern period, under Venetian domination, the town was known in Italian as Napoli di Romania, after the medieval usage of "Romania" to refer to the lands of the Byzantine Empire, and to distinguish it from Napoli (Naples) in Italy.
Also during the early modern period, but this time under Ottoman rule, the Turkish name of the town was Mora Yenişehir, after Morea, a medieval name for the Peloponnese, and "yeni şehir", the Turkish term for "new city" (apparently a translation from the Greek Νεάπολη, Italian Napoli). The Ottomans also called it Anabolı.
In the 19th century and early 20th century, the town was called indiscriminately Náfplion (Ναύπλιον) and Nafplio (Ναύπλιο) in modern Greek. Both forms were used in official documents and travel guides. This explains why the old form Náfplion (sometimes transliterated to Navplion) still occasionally survives up to this day.