Although PES was originally defined as a voluntary transaction, involving the conditional purchase of a well-defined environmental service by a buyer from a seller (Wunder 2005), most now recognise that such transactions often require states, donors and civil society to create new markets and associated institutions (Vatn 2010).
The history: The kilogram was originally defined as being equivalent to the mass of a liter of water.
This unit was originally defined as 100/27,316 of the triple point (equilibrium among the solid, liquid, and gaseous phases) of pure water.
It was originally defined as a one-sixth-pound candle of sperm wax, burning at the rate of 120 grains per hour.
The word pornography, derived from the Greek porni ("prostitute") and graphein ("to write"), was originally defined as any work of art or literature depicting the life of prostitutes.
The living wage was originally defined as "sufficient to provide an adequate level of warmth and shelter, a healthy palatable diet, social integration and avoidance of chronic stress for earners and dependants".
A nautical mile was originally defined as the length on the Earth's surface of one minute (1/60 of a degree) of arc along a meridian (north-south line of longitude).
The S-transform was originally defined as a method of determining the local spectrum of a time series, through the use of a translating, real Gaussian window that dilates to accomodate the different cycle durations of different frequencies.
The calorie was originally defined as the amount of heat required at a pressure of 1 standard atmosphere to raise the temperature of 1 gram of water 1° Celsius.
Because about three-fourths of the important known zoonoses are associated with domesticated animals, including pets, the term zoonosis was originally defined as a group of diseases that man is able to acquire from domesticated animals.
A public assembly was originally defined as "an assembly of 20 or more persons in a public place which is wholly or party open to the air", but this was amended by the Anti-social Behaviour Act 2003 to apply to assemblies of two or more persons.
