kou4
to knock; to kowtow

kou4
old variant of 叩; to knock

strokes 5
radical
strokes after radical 2
跪叩 跪叩 gui4 kou4
to kowtow

叩拜 叩拜 kou4 bai4
to bow in salute; to kowtow

叩关 叩關 kou4 guan1
to knock at the gate (old); to make an approach; to invade; to attack the goal (sports)

叩见 叩見 kou4 jian4
to kowtow in salute

叩门 叩門 kou4 men2
to knock on a door

叩球 叩球 kou4 qiu2
spike (volleyball)

叩首 叩首 kou4 shou3
to kowtow; also written 磕頭|磕头

叩头 叩頭 kou4 tou2
to kowtow (traditional greeting, esp. to a superior, involving kneeling and pressing one's forehead to the ground); also written 磕頭|磕头

叩谒 叩謁 kou4 ye4
to visit (esp. one's superiors)

叩应 叩應 kou4 ying4
call-in (loanword)

三跪九叩 三跪九叩 san1 gui4 jiu3 kou4
to kneel three times and kowtow nine times (formal etiquette on meeting the emperor)