Peninsula as we understand it today is claimed by some not to have had an exact equivalent in Classical Greek where the word for island, ‘nesos’, was used instead. Papamarinopoulos claims that the difference between ‘island’ and ‘peninsula’ was not recognised until the time of Herodotus.*[The term was also applied to a headland or promontory.]*Supporters of this interpretation are usually promoters of a location for Atlantis that is or was in ancient times a peninsula. The Latin word peninsula is a combination of two words ‘paena’ meaning ‘almost’ and ‘insula’ meaning ‘island’.
The assertion is that the ancient Greeks named peninsulas as if they were islands e.g. Peleponnese or Peloponnesus means the island of Pelops. Today the Greek word ‘chersonesus’ is used to describe a peninsula. The accepted etymology for this is that ‘khersos’ = dry land and ‘nesos’ = island which seems tautological since an island is dry land. On the other hand, if Chersonesus means the island of Cherson, who or what was Cherson originally.
Therefore, some doubt persists regarding the existence of an ancient Greek word for peninsula. If I may muddy the waters further, in Ireland there is a large peninsula named Inishowen or Owen’s Island!