knotty in WordNet English dictionary

1. making great mental demands; hard to comprehend or solve or believe
   "a baffling problem"; "I faced the knotty problem of what to have for breakfast"; "a problematic situation at home"
   baffling  elusive  knotty  problematic  problematical  tough 
   
2. highly complex or intricate and occasionally devious
   "the Byzantine tax structure"; "Byzantine methods for holding on to his chairmanship"; "convoluted legal language"; "convoluted reasoning"; "the plot was too involved"; "a knotty problem"; "got his way by labyrinthine maneuvering"; "Oh, what a tangled web we weave"- Sir Walter Scott; "tortuous legal procedures"; "tortuous negotiations lasting for months"
   Byzantine  convoluted  involved  knotty  tangled  tortuous 
   
3. used of old persons or old trees; covered with knobs or knots
   "gnarled and knotted hands"; "a knobbed stick"
   gnarled  gnarly  knotted  knotty  knobbed 
   
4. tangled in knots or snarls
   "a mass of knotted string"; "snarled thread"
   knotty  snarled  snarly