Related Clues:

• 'Fight Club' agent
• Caustic application
• It's used in soap-making
• Potassium hydroxide, e.g.
• Drain cleaner component
• Caustic potash
• NaOH, familiarly
• Wood ash product
• Drain opener
• Soapmaking ingredient
• Caustic alkali
• Caustic matter
• Alkali in cleansers
• KOH, to a layperson
• Drain-opening stuff