thermos
Definition
A vacuum flask or bottle designed to maintain the temperature of its contents, typically liquids like beverages, by using a double-walled construction with a vacuum between the walls.
A trademarked brand name originally for such insulated containers, now often used generically for any similar product.
Examples
I packed my thermos with scalding coffee this morning, and by afternoon it was still hot enough to melt the skepticism of my cold-hearted colleagues.
Her ancient thermos from college somehow keeps iced tea frosty longer than her ex's promises lasted.
In the middle of the desert hike, my thermos became the unsung hero, turning lukewarm water into a mirage of refreshment.
He swore his thermos could survive a nuclear winter, but it leaked soup all over his lap during a mild picnic.