水筒

1. Origins, structure, and basic meaning

• Structure: 水筒, read すいとう, combines water 水 with portable container 筒 as the name of a drink bottle.
• Basic usage: It denotes a closable container for carrying a drink, as in 水筒に麦茶を入れる.

2. Common pitfalls and similar expressions

• Scope and context
  • Some products retain temperature, but 水筒 itself does not require thermos insulation.