stumper

Từ điển WordNet v3.1 - WordNet Dictionary

noun

a particularly difficult or baffling question or problem
• Syn:
poser, toughie, sticker
• Derivationally related forms:
stump, pose (for: poser)
• Hypernyms:
problem

• Từ đồng nghĩa / Synonyms:
  poser, toughie, sticker