thermos

thermos — noun

1. a bottle or flask whose double wall has a vacuum-sealed gap, keeping whatever li

1.nounB1
Definition

a bottle or flask whose double wall has a vacuum-sealed gap, keeping whatever liquid is inside at the same temperature for a long time

Example

Andrés filled his thermos with hot coffee before the long train ride.

a thermos of + beverage for carrying

The children took a thermos of cold lemonade to the park on a summer afternoon.

Common collocations
  • a thermos of coffee/tea/soup
  • fill a thermos
  • drink from a thermos
  • pour from a thermos
  • pack a thermos
Synonyms
  • vacuum flask

    the technical, non-branded term; more common in British English

  • flask

    shorter and more general; can also refer to a hip flask for alcohol

  • insulated bottle

    describes the function clearly; often used for smaller, modern versions

Grammar Patterns

a thermos of [drink]

a thermos

the thermos

Usage Note

Originally a brand name, 'thermos' is now used in everyday speech for any vacuum flask regardless of the manufacturer.

Common Mistakes

Can you pour me a thermos?
Can you pour me some tea from your thermos?
'thermos' refers to the container itself, not the drink inside.
I bought a new thermos bottle.
I bought a new thermos.
Adding 'bottle' is redundant because 'thermos' already describes the type of container.

Synonym discussion

Sense: noun/1

'Thermos' is the most common everyday word in both British and American English, though technically it is a brand name. 'Vacuum flask' is the standard generic term, especially in British English for scientific or camping contexts. 'Insulated bottle' is a newer, more general term often used for modern stainless-steel versions that keep drinks cold or hot for up to 24 hours. 'Flask' is shorter but ambiguous: it can also mean a small bottle for alcohol carried in a pocket, or a laboratory container. In daily conversation, 'Can you pass me the thermos?' is natural, but in a product review you might see 'This insulated bottle keeps my tea hot for six hours.'

thermos ↗vacuum flaskinsulated bottleflask

Common collocations

Nouns

Phrases

  • a thermos of [drink]
  • fill a thermos
  • drink from a thermos
  • pour [drink] into a thermos

Prepositions

Etymology

GreekGermanEnglish

The word 'thermos' comes from the German brand Thermos GmbH, which began selling vacuum flasks in 1904. The company chose the name from the Greek word 'thermós' (θερμός), meaning 'hot'. The product became so popular that the brand name turned into the common word for any vacuum flask in many languages.