1. Making great mental demands; hard to comprehend or solve or believe
   "I faced the knotty problem of what to have for breakfast"
   - baffling, elusive, problematic, problematical, tough 
2. Used of old persons or old trees; covered with knobs or knots
   - gnarled, gnarly, knotted, knobbed 
3. Highly complex or intricate and occasionally devious
   "a knotty problem"
   - Byzantine, convoluted, involved, tangled, tortuous 
4. Tangled in knots or snarls
   - snarled, snarly

Derived forms: knottier, knottiest

See also: complex, crooked, difficult, hard, knot, knottiness, tangled

Encyclopedia: Knotty

• progressive vaccinia
• progressively
• progressiveness
• progressivism
• progressivity
• progymnosperm
• prohibit
• prohibited
• prohibition
• prohibition era
• Prohibition Party
• prohibitionist
• prohibitive
• prohibitively
• prohibitory
• proinflammatory
• project
• projected
• projectile
• projecting
• projection
• projection screen
• projectionist
• projective device
• projective geometry