竅 (aperture)

It means an opening, especially a bodily one. The Shuowen Jiezi, an early Chinese dictionary from the Eastern Han (25–220 CE), glosses 竅 as “open space” (空也).

In the Zhuangzi, an ancient Chinese text, 七竅 (“seven openings”) are the face’s openings for seeing, hearing, eating, and breathing. Chinese compounds turn this image into know-how: 竅門 and 訣竅 mean a method or knack; 一竅不通 means someone understands nothing.

竅 joins 穴, the opening-related meaning component, with 敫, which supplies its sound. Traditional dictionaries also connect its hole sense with 空 (“open space”) and 孔 (“hole”). Japanese dictionaries retain it for “hole.”