Lombok, is an island in West Nusa Tenggara province, Indonesia. It forms part of the chain of the Lesser Sunda Islands, with the Lombok Strait separating it from Bali to the west and the Alas Strait between it and Sumbawa to the east. It is roughly circular, with a "tail" (Sekotong Peninsula) to the southwest, about 70 kilometres (43 miles) across and a total area of about 4,566.54 square kilometres (1,763.15 square miles) including smaller offshore islands. The provincial capital and largest city on the island is Mataram.

Lombok is somewhat similar in size and density, and shares some cultural heritage with the neighboring island of Bali to the west. However, it is administratively part of West Nusa Tenggara, along with the larger but less densely populated island of Sumbawa to the east. Lombok is surrounded by a number of smaller islands locally called Gili.

The island was home to some 3,168,692 people as recorded in the decennial 2010 census and 3,758,631 in the 2020 Census; the official estimate as at 2024 was 4,056,621. Lomboq is Sasak for straight, honest.