1. The production and consumption of goods and services of a community regarded as a whole.
2. The prudent managing of resources to avoid extravagant expenditure or waste.
3. A saving or attempt to reduce expenditure.
4. Originally, the management of a household.
5. Current usage is sometimes a reference to that which is intended to be less expensive or to give better value.

The basic notion contained in the word economy is “household management”. It comes from Greek oikonomia, by way of French or Latin, and means the "steward of a household". This was a compound noun formed from oikos, "house" and nemein, “manage”. The original sense "household management" was extended into English. It broadened out in the 17th century to the management of a nation's resources, while the use of the derivative economics for the theoretical study of the creation and consumption of wealth dates from the early 19th century.

1. A deep vein thrombosis (blood clot along the wall of a blood vessel), usually in the leg, caused by sitting immobile for long periods in a cramped aircraft seat.

Once movement begins again the clot can move to heart or lungs, causing rapid death.

2. A form of phlebitis (inflammation of a vein) in which a blood clot forms in the lower leg after prolonged immobility in a cramped space; such as, traveling in a confined space, like a coach seat on a crowded air flight.

It is known as economy class syndrom because so many travelers are turning up with phlebitis.

A standard measure of the rate of motor vehicle fuel consumption, expressed as the total distance traveled divided by the amount of gasoline fuel consumed in doing this.

A general statement of this is based on the average mileage traveled per unit of fuel for a class of vehicles; for example, a certain car type in a given model year.

Fuel economy is most often measured by the distance a vehicle can travel with a given volume of fuel. In the U.S., fuel economy is measured in vehicle miles per gallon of fuel. In the European Union, liters per 100 kilometers is the preferred measure.

An economy based on the use of solar power; as well as, other renewable forms of energy that replace the use of fossil fuels.

An economy in which direct solar energy would be the primary energy source and hydrogen the secondary energy carrier.

Power from wind or photovoltaic systems would drive photo-electrolytic hydrogen production.