[jí shǒu]
thorny; troublesome; knotty; difficult to handle
a knotty [thorny] problem; the Gordian knot; a matter full of knots
棘手的問題
This is a sticky business.
這件事情很棘手。
When others interfere in the affair, it always makes troubles.
別人一卷入這一事件，棘手的事情就來了。