expression, godan verb (-ku)
touch the vital point; hit a sore spot
Used both literally (in martial arts or anatomy) and figuratively (to touch on a sensitive issue or weak point).
彼の一言が急所を突いて、彼女は黙り込んだ。
His remark hit a sore spot, and she fell silent.
柔道では相
In judo, striking an opponent's vital point is a foul.