What does the word nesia mean in Indonesia Melanesia Polynesia?

The word "nesia" comes from the Greek word nēsos/ νῆσος, meaning "island". It is used in the names of geographical regions to indicate a group of islands. For example, Indonesia is made up of over 17,000 islands, Melanesia consists of some 2,000 islands, and Polynesia is a region encompassing over 1,000 islands.