凹洞

Traditional form:

凹洞

Pinyin (reading):

āodòng

Definitions:

• cavity
• pit

Characters:

• 凹 - concave, hollow; depressed; pass, valley
• 洞 - cave, grotto, hole, ravine

Traditional characters:

• 凹 - concave, hollow; depressed; pass, valley
• 洞 - cave, grotto, hole, ravine