(of an object) Rigid; hard to bend; inflexible.
(of policies and rules and their application and enforcement) Inflexible; rigid.
(of a person) Formal in behavior; unrelaxed.
Harsh, severe.
He was eventually caught, and given a stiff fine.
(of muscles or parts of the body) Painful as a result of excessive or unaccustomed exercise.
My legs are stiff after climbing that hill yesterday.
Potent.
a stiff drink; a stiff dose; a stiff breeze.
Dead, deceased.
(of a penis) Erect.
(of whipping cream or egg whites) Beaten until so aerated that they stand up straight on their own.
beat the egg whites until they are stiff
Of an equation: for which certain numerical solving methods are numerically unstable, unless the step size is taken to be extremely small.
Keeping upright.