noun
ventilation hole; vent
Refers to an opening designed to allow air to circulate, commonly found in buildings, machinery, or containers.
この部屋には通風孔がないので、空気がこもりやすい。
This room has no ventilation hole, so the air tends to get stuffy.
機械の通風孔を定
Please clean the machine's vents regularly.
換気口 is a more general term for an air vent or ventilation opening, often used in building contexts, while 通風孔 specifically emphasizes an opening for air passage.
Compound of 通風 (tsūfū, 'ventilation') and 孔 (kō, 'hole') or 口 (kuchi, 'opening').