"Ananas (also Anana.) [So in most languages of Europe; app. from a native Peruvian name Nanas, it having been first seen by Europieans in Peru, and described under the name Nanas by Andre Therent, a monk, in 1555.
Through mistaking the final -s for a plural sign. Some have made sign. anana]
1) The pine-apple plant (Ananassa Sativa) or fruit.
2) .... ".

(From "The Compact OED")
It is a great reference tool.