What is the meaning of knotty?

adjective

• Making great mental demands; hard to comprehend or solve or believe.
  • usage: "a baffling problem"; "I faced the knotty problem of what to have for breakfast"; "a problematic situation at home"
  • synonyms: baffling, elusive, problematic, problematical, tough
• Used of old persons or old trees; covered with knobs or knots.
  • usage: "gnarled and knotted hands"; "a knobbed stick"
  • synonyms: gnarled, gnarly, knotted, knobbed
• Highly complex or intricate and occasionally devious.
  • usage: "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"
  • synonyms: Byzantine, convoluted, involved, tangled, tortuous
• Tangled in knots or snarls.
  • usage: "a mass of knotted string"; "snarled thread"
  • synonyms: snarled, snarly