孔 - cavity, hole, slit

perforation; punching; boring; drilling

Confucius and Mencius

ventilation hole; vent

foraminifer; foraminiferan

electron hole; hole

Indian peafowl (Pavo cristatus); common peafowl; blue peafowl

breathing hole

tape punch

index hole

northern maidenhair (Adiantum pedatum)

marigold (esp. the French marigold, Tagetes patula)

boring machine; punching machine; perforator