Macadamia is a genus of four species of trees indigenous to Australia, and constituting part of the plant family Proteaceae. They are native to north eastern New South Wales and central and south eastern Queensland. Three species of the genus are commercially important for their fruit, the macadamia nut /ˌmækəˈdeɪmiə/ (or simply macadamia), with a total global production of 160,000 tonnes (180,000 short tons) in 2015. Other names include Queensland nut, bush nut, maroochi nut, bauple nut, and Hawaii nut. In Australian Aboriginal languages, the fruit is known by names such as bauple, gyndl, jindilli, and boombera. It was an important source of bushfood for the Aboriginal peoples who were the original inhabitants of the area. Fresh macadamia nut with husk or pericarp cut in half Macadamia nut in its shell and a roasted nut Macadamia nut with sawn nutshell, and special key used to pry open the nut

The nut was first commercially produced on a wide scale in Hawaii, where it was introduced in the 1880s, and for some time they were the world's largest producer. South Africa has been the world's largest producer of the macadamia in the 2010s.

Compared with other common edible nuts, such as almonds and cashews, macadamias are high in total fat and relatively low in protein. They have a high amount of monounsaturated fats (59% of total content, table) and contain, as 17% of total fat, the monounsaturated fat, omega-7 palmitoleic acid.

Eating peanuts and tree nuts (e.g., walnuts, almonds, and pistachios) may reduce the risk of heart disease when consumed as part of a diet that is nutritionally adequate and within calorie needs. Because nuts and seeds are high in calories, eat them in small portions and use them to replace other protein foods, like some meat or poultry, rather than adding them to what you already eat. In addition, choose unsalted nuts and seeds to help reduce sodium intakes.