cool as a cucumber

slang Calm and composed, especially in times of stress. I was petrified to take the stage, but Alice was as cool as a cucumber. Practicing meditation has helped me to be as cool as a cucumber in times of trouble. Call Drew—he's always cool as a cucumber about stuff like this. He'll help us for sure.

extremely calm; imperturbable. (*Also: as ~.) Joan felt nervous, but she acted as cool as a cucumber. The politician kept cool as a cucumber throughout the interview with the aggressive journalist.

Calm and composed, self-possessed, as in Despite the mishap Margaret was cool as a cucumber. This idiom may be based on the fact that in hot weather the inside of cucumbers remains cooler than the air. [c. 1600] For a synonym, see cool, calm, and collected.

If someone is as cool as a cucumber, they are very relaxed, calm, and unemotional. Never once did she gasp for air or mop her brow. She was as cool as a cucumber. Karen is usually as cool as a cucumber when she appears on television.

Perfectly composed, self-possessed. The cool temperature of cucumbers apparently was observed long ago, and indeed one modern writer quotes recent evidence that the inside of a field cucumber on a warm day is 20 degrees cooler than the air. Beaumont and Fletcher described “young maids . . . as cold as cucumbers” (Cupid’s Revenge, 1615, 1.1), and in 1732 John Gay, in a New Song on New Similies, wrote, “I . . . cool as a cucumber could see the rest of womankind.” A more recent version with essentially the same meaning is cool, calm, and collected, which likewise owes its popularity to its alliterative appeal. The earliest (and only partial) reference cited by the OED is Sir J. Hannen’s in an 1885 law journal: “A calm and collected and rational mind.”