气孔 (qì kǒng) literally means 'air opening' — 气 (qì) means 'air' or 'gas', and 孔 (kǒng) means 'hole' or 'pore'. In botany, it refers specifically to microscopic pores found mainly on the undersides of plant leaves and stems, through which gases like carbon dioxide, oxygen, and water vapor are exchanged with the atmosphere. These tiny structures are essential for photosynthesis and transpiration.

While 气孔 can occasionally be used in engineering or architecture to mean 'vent' or 'air vent', its primary and most frequent usage is in biology and plant science. It is a technical term commonly encountered in middle-school and high-school science textbooks, as well as in agricultural and horticultural contexts. Unlike general terms for openings (e.g., 口 or 洞), 气孔 emphasizes function — gas exchange — rather than size or shape.