Translation guide
A thermos is a vacuum-insulated container that keeps drinks hot or cold. In Japanese, the most common equivalent is 魔法瓶 (mahōbin), but other terms exist depending on context.
The general term for a thermos, used for keeping beverages at temperature.
The standard Japanese word for a thermos or vacuum flask. Literally 'magic bottle'. Used for both hot and cold drinks.
魔法瓶に熱いコーヒーを入れた。
I put hot coffee in the thermos.
この魔法瓶は保温性が高い。
This thermos has excellent heat retention.
A common brand name (Thermos) used generically, similar to English. Often used in casual conversation.
サーモスを持ってピクニックに行こう。
Let's bring a thermos to the picnic.
Literally 'heat-retaining pot'. Often used for larger tabletop dispensers, but can refer to personal thermoses.
保温ポットにお茶を用意しました。
I prepared tea in the thermos.
General term for a water bottle or canteen. Not specifically vacuum-insulated, but often used for any portable drink container.
水筒 does not necessarily imply vacuum insulation; it can be a simple bottle.
子供は水筒を持って学校に行く。
Children take a water bottle to school.
A compact, often cylindrical thermos designed for one person's beverage.
Portable thermos. Emphasizes the small, personal size.
携帯魔法瓶に紅茶を入れて通勤する。
I put tea in my portable thermos for the commute.
Literally 'my bottle'. A trendy term for a personal reusable bottle, often insulated. Common in eco-friendly contexts.
マイボトルを持ち歩いて、プラスチックを減らそう。
Let's carry our own bottles to reduce plastic.
A large, often pump-action thermos used for serving hot drinks to a group.
Airpot. A large insulated dispenser with a pump top, common in offices and meetings.
会議室にエアーポットを用意してください。
Please set up an airpot in the meeting room.
Can also refer to larger tabletop dispensers, though less specific than エアーポット.
保温ポットからコーヒーを注ぐ。
Pour coffee from the thermos dispenser.
魔法瓶 specifically means a vacuum-insulated flask. 水筒 is a broader term for any portable drink container, including non-insulated bottles. If insulation is important, use 魔法瓶.
魔法瓶は熱い飲み物を長時間保温できる。
A thermos can keep hot drinks warm for a long time.
水筒は必ずしも保温機能があるとは限らない。
A water bottle does not necessarily have insulation.
Like in English, brand names such as サーモス (Thermos) or 象印 (Zojirushi) are often used generically. In casual speech, saying サーモス is perfectly natural.
魔法瓶にお湯を入れた。
I filled the thermos with hot water.
彼女はいつも緑茶の入った魔法瓶を持ち歩いている。
She always carries a thermos of green tea.