knotty

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"

used of old persons or old trees; covered with knobs or knots; "gnarled and knotted hands"; "a knobbed stick"

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"

tangled in knots or snarls; "a mass of knotted string"; "snarled thread"