knotty
adjective /ˈnɒti/
  /ˈnɑːti/
(comparative knottier, superlative knottiest)
- complicated and difficult to solve复杂的;难以解决的;棘手的 - a knotty problem棘手的问题 
 
- a knotty problem
- having parts that are hard and twisted together有节的;缠绕在一起的 - the knotty roots of the old oak tree盘根错节的老橡树根 
 
- the knotty roots of the old oak tree