Senses
洞 hole
hole; cavity; cave
洞 thoroughly
(bound form) thoroughly; penetratingly; clearly
洞 zero
the number zero, used when spelling out numbers to avoid confusion
洞 [place name]
(bound form) used in the name of Hongtong County in Shanxi province
洞 surname
a Chinese surname
洞 to pierce
(bound form) to penetrate; to pierce; to connect