口
くち · kuchi · JLPT N5 · noun
opening
👄 口 is a mouth drawn as an open square; an opening for a job too
The character began as a drawing of an open mouth. Japanese extends kuchi to any opening: an entrance, a slot, a vacancy. A job opening is a mouth the company needs to fill, the same way English says an opening.
口 — pictograph of an open mouth
口 is one of the oldest pictographs in Chinese, originally drawn as a simple outline of an open mouth. Its core meaning 'mouth' extended naturally to 'opening' or 'entrance', as in 入口 (entrance). It also serves as a common radical in characters related to speech, eating, or apertures.