knotty
🇺🇸
/ˈnɑːti/
🇬🇧
/ˈnɒti/
hard to solve or understand
The knotty math problem took hours to solve.
这个复杂的数学问题花了几个小时才解决。
full of knots or twists
The knotty wood was hard to cut.
多节的木头很难切割。