Stiff may refer to:

• Stiffness - scientific explanation
• Stiff can also be used as a slang word for when a customer fails to tip a server.
• Stiff also has two uses in professional wrestling.
  • Stiff (professional wrestling) - Used to describe how hard a wrestler is attacking his/her opponent.
  • Also a term used when a promoter does not pay his/her wrestlers.
• Stiff equation - equations that exhibit smooth behaviour, then sudden changes
• The Curious Lives of Human Cadavers - a book about corpses by Mary Roach.
• Stiff (movie) - an Australian movie starring David Wenham.