Know how to use "fewer" and "less"? Find out.
1590s, from Italian pistacchio, from Latin pistacium "pistachio nut," from Greek pistakion "pistachio nut," from pistake "pistachio tree," from Persian pistah "pistachio." Borrowed earlier (1530s) as pystace, from Old French form pistace (13c.), which also is from the Italian word.