The pistachio, a member of the cashew family, is a small tree originating in Persia. The tree produces seeds that are widely consumed as food. The word can be countable or uncountable, meaning its plural is with or without an 's'.

The Anacardiaceae, commonly known as the cashew family or sumac family, are a family of flowering plants, including about 83 genera with about 860 known species. Members of the Anacardiaceae bear fruits that are drupes and in some cases produce urushiol, an irritant. The Anacardiaceae include numerous genera, several of which are economically important, notably cashew, mango, Chinese lacquer tree, yellow mombin, Peruvian pepper, poison ivy, poison oak, sumac, smoke tree, marula and cuachalalate. The genus Pistacia is now included, but was previously placed in its own family, the Pistaciaceae.