conundrum /kə-nunˈdrəm/

1. A riddle, esp one whose answer is a play on words
2. Any puzzling question

• plumbite
• plumbites
• plumbless
• plumb line
• plumb lines
• plum-blossom
• plumbosolvency
• plumbosolvent
• plumbous
• plumb rule
• plumb rules
• plumbs
• plumbum
• plumbums
• plum-cake
• plum-colour
• plumcot
• plumcots
• plum curculio
• plumdamas
• psychotic
• psychoticism
• psychoticisms
• psychotics
• psychotomimetic