洞 On the HSK 5 vocabulary list, at CEFR level C1. dòng ㄉㄨㄥˋ cave hole zero (unambiguous spoken form when spelling out numbers) Words with 洞 Starting with 洞 洞口 洞穴 Ending with 洞 门洞 山洞 Words with 洞 Starting with 洞 洞口 洞穴 Ending with 洞 門洞 山洞 Where 洞 is used Example sentences and grammar articles using 洞 Sources CC-CEDICT, CC BY-SA 4.0 pinyinjs, Apache-2.0 国际中文教育中文水平等级标准, 中华人民共和国教育部, MIT