The South Island forms one of the two major islands of New Zealand, the other being the North Island. The Maori name for the South Island is Te Wai Pounamu which means "The Greenstone Water" (greenstone being jade).
Historical Note: In the 19th century, today's South Island bore the name Middle Island, and the name South Island referred to today's Stewart Island.
Historic provinces of the South Island:
Shibboleth Warning: maps and non-New Zealanders say "South Island"; but genuine Kiwis say "the South Island", with a definite article. Commonly known as the Mainland in New Zealand.