noun
thermos
THUR-mos
noun
1
An insulated flask that keeps drinks or food hot or cold.
"She packed a thermos of coffee for the road trip."
How to Use Thermos
Learner’s notesIn plain EnglishA vacuum-sealed flask that keeps drinks hot or cold for hours.
Common mistake
Originally a brand name; now used generically for any insulated flask, similar to "hoover" for vacuum cleaners.
Common pairings
a thermos of tea
thermos flask
Word Forms
thermoses plural, thermoi plural, thermoi plural
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She packed a _____ of coffee for the road trip.
Etymology
Originally a trademark, from Greek thermos ("warm, hot").