pitahaya
Concise Oxford English Dictionary © 2008 Oxford University Press:
pitahaya /ˌpɪtəˈhʌɪə/
▶noun a saguaro or other tall cactus of Mexico and the south-western US.
■ the edible fruit of the pitahaya.
– origin C18: from Sp., from Haitian Creole.
'pitahaya' also found in these Oxford entries:

