1. (

• baffling ,
• elusive ,
• knotty ,
• problematic ,
• problematical ,
• tough ,

) 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" ;

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" ;

3. (

• Byzantine ,
• convoluted ,
• involved ,
• knotty ,
• tangled ,
• tortuous

) 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" ;

4. (

• knotty ,
• snarled ,
• snarly

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