dōng
(onom.) boom (of a drum)
knock (on the door)
This is an interjection or onomatopoeia — it represents a sound.
黑咕隆咚
hēi gu lōng dōng
pitch-black
叮咚
dīng dōng
(onom.) ding dong
咕咚
gū dōng
splash
咚咚
dōng dong
Dongdong, cheerleading mascot of 2008 Beijing Olympics
dōng dōng
(onom.) thud
壁咚
bì dōng
(slang) to kabedon; to corner (sb in whom one has a romantic interest) against a wall (loanword from Japanese 壁ドン "kabedon")