Croatoan

Croatoan was an island near the island of Roanoke. It was used by a group of alien entities to capture and hold prisoners, including the colonists of Roanoke and the Vikings. (AUDIO: Voyage to the New World)

Behind the scenes
Big Finish at least initially misspelled this word on their printed synopsis, calling it Croaton on Voyage to the New World's official webpage.

Moreover, actor Christopher Benjamin's pronunciation of the word is wholly wrong, but perhaps intentionally so. By having him avoid any known American pronunciation — and instead say the first two syllables, Cro-at, like the demonym for "a person from Croatia" — Benjamin may have been trying to logically suggest that his 19th century character was more familiar with European geography than American.

Furthermore, the play's widespread use of Croatoan — instead of Croatan — is unusual, since the additional "o" is reflective of 16th century English. In most performed adventures, the Doctor is seen to be using the modern-day terms for places and people — London instead of Londinium, New York instead of New Amsterdam, Edinburgh instead of Eidyn. In this case, though, he goes for the term of antiquity, which is perhaps consistent with the Sixth Doctor's more professorial inclinations. In reality, the second "o" has been absent in common American speech for several centuries, resurfacing generally only in scholarly references when there is a need to distinguish between the modern day and the past.