Translation guide
A container that keeps liquids hot or cold by using a vacuum between double walls. In Japanese, the most common term is 魔法瓶 (mahōbin), literally 'magic bottle'. Other terms exist but are less common.
To refer to a container that keeps drinks hot or cold, typically used for coffee, tea, or water.
The standard word for a vacuum flask. Literally 'magic bottle'. Used in everyday conversation.
I put hot coffee in the vacuum flask.
From the brand name 'Thermos'. Often used generically, like 'Thermos' in English. Common in casual contexts.
I put tea in a Thermos and take it with me.
Literally 'heat-retaining bottle'. Often used for modern stainless steel flasks, especially those for cold drinks as well.
Technical term: 'vacuum-insulated bottle'. Used in product descriptions or specifications.
This vacuum flask keeps things hot very well.
When I put ice in the insulated bottle, it stayed cold the whole time.
This vacuum-insulated bottle is lightweight and convenient to carry.