The general tendency for a

person to be willing to give up less of good Y to get one more unit of good X,

while at the same time remaining indifferent as the quantity of good X

increases.

The effect of a change in

the price of a good on the quantity of the good consumed, other things

remaining the same.

The analysis of the

increase in satisfaction consumers gain from consuming an extra unit of a good.

It predicts the law of demand.

The marginal utility from a

good that results from spending one more dollar on it. It is calculated as the

marginal utility from the good divided by its price.

Any combination of goods

and services within the budget of an economic agent.

Money that a person or a

business receives in return for working, providing a product or service, or

investing capital.

The relation that shows how

quantity demanded varies with price, holding all other factors constant. It is

illustrated by a demand curve and described by a demand schedule.    

A pair of goods that must

be consumed with one another in a fixed proportion to satisfy a want or need.