a climbing plant cultivated as a garden vegetable for its the long green edible fruit of a climbing plant, eaten raw as a salad vegetable: Cucumis sativus
a fruit of this plant, used as a vegetable, esp in salads
A cucumber should be well sliced, and dressed with pepper and vinegar, and then thrown out, as good for nothing — Dr Johnson
as cool as a cucumber
perfectly calm and composed
[Middle English from early French cocombre, from Latin cucumer-, cucumis]