Adjective knotty has 3 senses
  1. baffling, knotty, problematic, problematical - making great mental demands; hard to comprehend or solve; "a baffling problem"; "I faced the knotty problem of what to have for breakfast"; "a problematic situation at home"
    Antonym: easy (indirect, via difficult)
  2. gnarled, gnarly, knotted, knotty, knobbed - used of old persons or old trees; covered with knobs or knots; "gnarled and knotted hands"; "a knobbed stick"
    Antonym: straight (indirect, via crooked)
  3. Byzantine, convoluted, intricate, involved, knotty, labyrinthine, tangled, tortuous - highly involved or intricate; "the Byzantine tax structure"; "convoluted legal language"; "convoluted reasoning"; "intricate needlework"; "an intricate labyrinth of refined phraseology"; "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"
    Antonym: simple (indirect, via complex)