What is "pistachio nut"

Pistachio \Pis*ta"chio\, n. [It. pistacchio (cf. Sp. pistacho, F. pistache), fr. L. pistacium, Gr. ?, ?, fr. Per. pistah. Cf. Fistinut.] (Bot.) The nut of the Pistacia vera, a tree of the order Anacardiace[ae], containing a kernel of a pale greenish color, which has a pleasant taste, resembling that of the almond, and yields an oil of agreeable taste and odor; -- called also pistachio nut. It is wholesome and nutritive. The tree grows in Arabia, Persia, Syria, and Sicily. [Written also pistachia.]

2. The small anacardiaceous tree ( Pistacia vera), of southern Europe and Asia Minor, which bears the pistachio nut. Called also pistache.

3. (Cookery) The flavor of the pistachio nut, or an ice or confection flavored with it.

4. Pistachio green.

n. nut of Mediterranean trees having an edible green kernel [syn: pistachio]