well

丼 depicts a well which is surrounded by railings with an object inside it. Both 丼 and 井 came from the same origin and shared the same meaning in the past. However, now we seldom use 丼 to describe a well, 丼 is used as a onomatopoeia which imitates the sound of something drops in the water (丼 also pronounces dan3 in Putongua or dam2 in Cantonese). On the other hand, in Japanese, 丼 is used to describe a bowl since the shape of 丼 looked similar to the ancient Japanese lunchbox, and the pronunciation of 丼in Japanese, which is donburi, partially preserves the ancient pronunciation of this HanZi.