換気扇（かんきせん、kankiseん）
- ventilation fan

The Japanese word 換気扇 (かんきせん) means "ventilation fan" or "exhaust fan." It refers to a mechanical device used to circulate air, typically by removing stale or polluted air from a room or enclosed space and replacing it with fresh air. 換気扇s are common in kitchens, bathrooms, and other areas where odors, steam, or fumes are produced. They help to prevent the build-up of moisture, mold, and unpleasant smells, as well as improve air quality.

⚫︎換気扇を回してください。 Translation: Please turn on the ventilation fan. ⚫︎キッチンに新しい換気扇を取り付けました。 Translation: I installed a new ventilation fan in the kitchen. ⚫︎換気扇の音がうるさいです。 Translation: The ventilation fan is noisy.

You use 換気扇 when you are talking about the fan itself, or when you are requesting someone to turn on or off the fan. You might use it when discussing ventilation issues or the placement of the fan in a building. It's appropriate in both formal and informal contexts.

換気扇 is typically written in kanji 換気扇. The reading is かんきせん in hiragana. There are no other common ways to write this word. The okurigana is standard, with no variations.

There are no direct perfect synonyms for 換気扇 in Japanese, as it is a specific technical term. However, depending on the context, you might use more general terms that relate to air circulation or exhaust, such as: ⚫︎ 換気（かんき） - ventilation ⚫︎ 排気ファン（はいきファン） - exhaust fan (loan word)

There aren't specific antonyms in the same sense, as it’s a physical item. However, words or phrases that relate to the opposite action or concept could include: ⚫︎ 閉じる（とじる） - to close ⚫︎ 空気を止める（くうきをとめる） - to stop the air

お風呂に入った後、換気扇を忘れずに回してください。 ・Translation: After taking a bath, don't forget to turn on the ventilation fan. ・Explanation: This sentence emphasizes the importance of using the 換気扇 to remove moisture from a bathroom after use.

新しいアパートの換気扇はとても静かで良いです。 ・Translation: The ventilation fan in the new apartment is very quiet and good. ・Explanation: This sentence is describing the quality of 換気扇 in new apartment.

換気扇 is a compound word: ⚫︎ 換気（かんき） means "ventilation" or "airing." 換気 is derived from 換（かん） meaning "to exchange" or "to change" and 気（き） meaning "air" or "atmosphere." ⚫︎ 扇（せん） means "fan." Therefore, 換気扇 literally means "ventilation fan."