'banana' originates from Spanish/Portuguese, specifically the word 'banana', which itself likely came from West African languages (possibly Wolof or Mandinka).

'banana' entered English in the late 16th century from Spanish or Portuguese 'banana', the term having been borrowed from West African sources; it kept a similar form into modern English as 'banana'.

Initially it referred to the tropical fruit introduced into European languages; over time the primary meaning has remained the fruit, while a slang sense 'bananas' meaning 'crazy' developed in 20th-century English.