Simple Definition of thermos

from our Learner's Dictionary

thermos

noun

plural thermoses
: a container that keeps liquids hot or cold for long periods of time

called also (US) thermos bottle, ((British)) flask, ((British)) vacuum flask

Cite this Entry

“Thermos.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/thermos. Accessed 17 Apr. 2026.

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