knotty

形容词 knotty:

1. making great mental demands; hard to comprehend or solve or believe
   同义词：baffling, problematic, problematical, tough
2. used of old persons or old trees; covered with knobs or knots
   同义词：gnarled, gnarly, knotted, knobbed
3. highly complex or intricate
   同义词：Byzantine, convoluted, involved, tangled, tortuous
4. tangled in knots or snarls
   同义词：knotted, snarled, snarly

knot.ty

adj.（形容词）
knot.ti.er,knot.ti.est
Tied or snarled in knots.
打结的：用结系或捆的
Covered with knots or knobs; gnarled.
多节的，多瘤的：布满节或球状突出物的；多瘤的
Difficult to understand or solve; puzzlingly intricate.See Synonyms at complex
棘手的：很难理解或解决的；令人困惑地错综复杂的参见 complex

【引伸】
knot.tiness
n.（名词）