a line showing the possible combinations of two goods that a consumer can purchase

(a) A line showing all combinations of quantities of good X and good Y the consumer can buy given a specific income. Its slope equals -1 times the price of good X divided by the price of good Ywhen X is measured along the horizontal axis and Y is measured along the vertical axis. The Yintercept in this case equals income divided by the price of Y. (MY)(b) Given a specific level of income (I) and assuming there are only two goods (x & y) and further assuming prices are Px and Py respectively, then a budget line can be plotted showing all commodity combinations of x and and  that a consumer can afford. (HHC)

A line that describes the limits to consumption choices and that depends on a consumer's budget and the prices of goods and services. (p. 230)