Definition of "cucumber"

ASPARAGUS, cauliflowers, imperial Sileſia, royal and cabbage lettuces, burnet, purſlain, cucumbers, naſturtian flowers, peaſe and beans ſown in October, artichokes, ſcarlet ſtrawberries, and kidney beans.

1767, A Lady [Hannah Glasse], The Art of Cookery Made Plain and Eaſy […] ‎, page 326

[…] for it has been a common ſaying of phyſicians in England, that a cucumber ſhould be well ſliced, and dreſſed with pepper and vinegar, and then thrown out, as good for nothing.

1785, James Boswell, quoting Samuel Johnson, Journal of a Tour to the Hebrides with Samuel Johnſon […] ‎, London: Henry Baldwin, page 356

"Why, pepper and salt your reasons!" cried Curl, forgetting to look at the door for a moment: "your pamphlet has talent; but talent is like a cucumber, nothing without the dressing. You must be more personal."

1837, L[etitia] E[lizabeth] L[andon], “Publishing”, in Ethel Churchill: Or, The Two Brides. […], volume II, London: Henry Colburn, […], page 14

Just a few tips will help even the most anxious of us get a bit of control over the presentation of information and thus appear to be that "cool cucumber" in cognito!

1986, Linking Technology and Users, page 41

The guy's a real cucumber.

1999, Mark Grantham, The Brewery, page 275

That Wolf is one cool cucumber.

2002, Margaret Fisher, Putting on Mock Trials, page 29

"You're smart," says Irv, pointing at her and nodding his head. "A smart cucumber."

2018, Derek B. Miller, American By Day, page 65